/*
 * Copyright 2019 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Author: AMD
 */

#include <drm/drm_dsc.h>
#include "dc_hw_types.h"
#include "dsc.h"
#include <drm/drm_dp_helper.h>
#include "dc.h"
#include "rc_calc.h"
#include "fixed31_32.h"

/* This module's internal functions */

/* default DSC policy target bitrate limit is 16bpp */
static uint32_t dsc_policy_max_target_bpp_limit = 16;

/* default DSC policy enables DSC only when needed */
static bool dsc_policy_enable_dsc_when_not_needed;

static bool dsc_policy_disable_dsc_stream_overhead;

/* Forward Declerations */
static void get_dsc_bandwidth_range(
		const uint32_t min_bpp_x16,
		const uint32_t max_bpp_x16,
		const uint32_t num_slices_h,
		const struct dsc_enc_caps *dsc_caps,
		const struct dc_crtc_timing *timing,
		struct dc_dsc_bw_range *range);

static uint32_t compute_bpp_x16_from_target_bandwidth(
		const uint32_t bandwidth_in_kbps,
		const struct dc_crtc_timing *timing,
		const uint32_t num_slices_h,
		const uint32_t bpp_increment_div,
		const bool is_dp);

static void get_dsc_enc_caps(
		const struct display_stream_compressor *dsc,
		struct dsc_enc_caps *dsc_enc_caps,
		int pixel_clock_100Hz);

static bool intersect_dsc_caps(
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		const struct dsc_enc_caps *dsc_enc_caps,
		enum dc_pixel_encoding pixel_encoding,
		struct dsc_enc_caps *dsc_common_caps);

static bool setup_dsc_config(
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		const struct dsc_enc_caps *dsc_enc_caps,
		int target_bandwidth_kbps,
		const struct dc_crtc_timing *timing,
		int min_slice_height_override,
		int max_dsc_target_bpp_limit_override_x16,
		struct dc_dsc_config *dsc_cfg);

static struct fixed31_32 compute_dsc_max_bandwidth_overhead(
		const struct dc_crtc_timing *timing,
		const int num_slices_h,
		const bool is_dp);

static bool dsc_buff_block_size_from_dpcd(int dpcd_buff_block_size, int *buff_block_size)
{

	switch (dpcd_buff_block_size) {
	case DP_DSC_RC_BUF_BLK_SIZE_1:
		*buff_block_size = 1024;
		break;
	case DP_DSC_RC_BUF_BLK_SIZE_4:
		*buff_block_size = 4 * 1024;
		break;
	case DP_DSC_RC_BUF_BLK_SIZE_16:
		*buff_block_size = 16 * 1024;
		break;
	case DP_DSC_RC_BUF_BLK_SIZE_64:
		*buff_block_size = 64 * 1024;
		break;
	default: {
			dm_error("%s: DPCD DSC buffer size not recognized.\n", __func__);
			return false;
		}
	}

	return true;
}


static bool dsc_line_buff_depth_from_dpcd(int dpcd_line_buff_bit_depth, int *line_buff_bit_depth)
{
	if (0 <= dpcd_line_buff_bit_depth && dpcd_line_buff_bit_depth <= 7)
		*line_buff_bit_depth = dpcd_line_buff_bit_depth + 9;
	else if (dpcd_line_buff_bit_depth == 8)
		*line_buff_bit_depth = 8;
	else {
		dm_error("%s: DPCD DSC buffer depth not recognized.\n", __func__);
		return false;
	}

	return true;
}


static bool dsc_throughput_from_dpcd(int dpcd_throughput, int *throughput)
{
	switch (dpcd_throughput) {
	case DP_DSC_THROUGHPUT_MODE_0_UNSUPPORTED:
		*throughput = 0;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_170:
		*throughput = 170;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_340:
		*throughput = 340;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_400:
		*throughput = 400;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_450:
		*throughput = 450;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_500:
		*throughput = 500;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_550:
		*throughput = 550;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_600:
		*throughput = 600;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_650:
		*throughput = 650;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_700:
		*throughput = 700;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_750:
		*throughput = 750;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_800:
		*throughput = 800;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_850:
		*throughput = 850;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_900:
		*throughput = 900;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_950:
		*throughput = 950;
		break;
	case DP_DSC_THROUGHPUT_MODE_0_1000:
		*throughput = 1000;
		break;
	default: {
			dm_error("%s: DPCD DSC throughput mode not recognized.\n", __func__);
			return false;
		}
	}

	return true;
}


static bool dsc_bpp_increment_div_from_dpcd(uint8_t bpp_increment_dpcd, uint32_t *bpp_increment_div)
{
	// Mask bpp increment dpcd field to avoid reading other fields
	bpp_increment_dpcd &= 0x7;

	switch (bpp_increment_dpcd) {
	case 0:
		*bpp_increment_div = 16;
		break;
	case 1:
		*bpp_increment_div = 8;
		break;
	case 2:
		*bpp_increment_div = 4;
		break;
	case 3:
		*bpp_increment_div = 2;
		break;
	case 4:
		*bpp_increment_div = 1;
		break;
	default: {
		dm_error("%s: DPCD DSC bits-per-pixel increment not recognized.\n", __func__);
		return false;
	}
	}

	return true;
}


bool dc_dsc_parse_dsc_dpcd(const struct dc *dc,
		const uint8_t *dpcd_dsc_basic_data,
		const uint8_t *dpcd_dsc_branch_decoder_caps,
		struct dsc_dec_dpcd_caps *dsc_sink_caps)
{
	if (!dpcd_dsc_basic_data)
		return false;

	dsc_sink_caps->is_dsc_supported =
		(dpcd_dsc_basic_data[DP_DSC_SUPPORT - DP_DSC_SUPPORT] & DP_DSC_DECOMPRESSION_IS_SUPPORTED) != 0;
	if (!dsc_sink_caps->is_dsc_supported)
		return false;

	dsc_sink_caps->dsc_version = dpcd_dsc_basic_data[DP_DSC_REV - DP_DSC_SUPPORT];

	{
		int buff_block_size;
		int buff_size;

		if (!dsc_buff_block_size_from_dpcd(dpcd_dsc_basic_data[DP_DSC_RC_BUF_BLK_SIZE - DP_DSC_SUPPORT],
										   &buff_block_size))
			return false;

		buff_size = dpcd_dsc_basic_data[DP_DSC_RC_BUF_SIZE - DP_DSC_SUPPORT] + 1;
		dsc_sink_caps->rc_buffer_size = buff_size * buff_block_size;
	}

	dsc_sink_caps->slice_caps1.raw = dpcd_dsc_basic_data[DP_DSC_SLICE_CAP_1 - DP_DSC_SUPPORT];
	if (!dsc_line_buff_depth_from_dpcd(dpcd_dsc_basic_data[DP_DSC_LINE_BUF_BIT_DEPTH - DP_DSC_SUPPORT],
									   &dsc_sink_caps->lb_bit_depth))
		return false;

	dsc_sink_caps->is_block_pred_supported =
		(dpcd_dsc_basic_data[DP_DSC_BLK_PREDICTION_SUPPORT - DP_DSC_SUPPORT] &
		 DP_DSC_BLK_PREDICTION_IS_SUPPORTED) != 0;

	dsc_sink_caps->edp_max_bits_per_pixel =
		dpcd_dsc_basic_data[DP_DSC_MAX_BITS_PER_PIXEL_LOW - DP_DSC_SUPPORT] |
		dpcd_dsc_basic_data[DP_DSC_MAX_BITS_PER_PIXEL_HI - DP_DSC_SUPPORT] << 8;

	dsc_sink_caps->color_formats.raw = dpcd_dsc_basic_data[DP_DSC_DEC_COLOR_FORMAT_CAP - DP_DSC_SUPPORT];
	dsc_sink_caps->color_depth.raw = dpcd_dsc_basic_data[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];

	{
		int dpcd_throughput = dpcd_dsc_basic_data[DP_DSC_PEAK_THROUGHPUT - DP_DSC_SUPPORT];

		if (!dsc_throughput_from_dpcd(dpcd_throughput & DP_DSC_THROUGHPUT_MODE_0_MASK,
									  &dsc_sink_caps->throughput_mode_0_mps))
			return false;

		dpcd_throughput = (dpcd_throughput & DP_DSC_THROUGHPUT_MODE_1_MASK) >> DP_DSC_THROUGHPUT_MODE_1_SHIFT;
		if (!dsc_throughput_from_dpcd(dpcd_throughput, &dsc_sink_caps->throughput_mode_1_mps))
			return false;
	}

	dsc_sink_caps->max_slice_width = dpcd_dsc_basic_data[DP_DSC_MAX_SLICE_WIDTH - DP_DSC_SUPPORT] * 320;
	dsc_sink_caps->slice_caps2.raw = dpcd_dsc_basic_data[DP_DSC_SLICE_CAP_2 - DP_DSC_SUPPORT];

	if (!dsc_bpp_increment_div_from_dpcd(dpcd_dsc_basic_data[DP_DSC_BITS_PER_PIXEL_INC - DP_DSC_SUPPORT],
										 &dsc_sink_caps->bpp_increment_div))
		return false;

	if (dc->debug.dsc_bpp_increment_div) {
		/* dsc_bpp_increment_div should onl be 1, 2, 4, 8 or 16, but rather than rejecting invalid values,
		 * we'll accept all and get it into range. This also makes the above check against 0 redundant,
		 * but that one stresses out the override will be only used if it's not 0.
		 */
		if (dc->debug.dsc_bpp_increment_div >= 1)
			dsc_sink_caps->bpp_increment_div = 1;
		if (dc->debug.dsc_bpp_increment_div >= 2)
			dsc_sink_caps->bpp_increment_div = 2;
		if (dc->debug.dsc_bpp_increment_div >= 4)
			dsc_sink_caps->bpp_increment_div = 4;
		if (dc->debug.dsc_bpp_increment_div >= 8)
			dsc_sink_caps->bpp_increment_div = 8;
		if (dc->debug.dsc_bpp_increment_div >= 16)
			dsc_sink_caps->bpp_increment_div = 16;
	}

	/* Extended caps */
	if (dpcd_dsc_branch_decoder_caps == NULL) { // branch decoder DPCD DSC data can be null for non branch device
		dsc_sink_caps->branch_overall_throughput_0_mps = 0;
		dsc_sink_caps->branch_overall_throughput_1_mps = 0;
		dsc_sink_caps->branch_max_line_width = 0;
		return true;
	}

	dsc_sink_caps->branch_overall_throughput_0_mps =
		dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_OVERALL_THROUGHPUT_0 - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0];
	if (dsc_sink_caps->branch_overall_throughput_0_mps == 0)
		dsc_sink_caps->branch_overall_throughput_0_mps = 0;
	else if (dsc_sink_caps->branch_overall_throughput_0_mps == 1)
		dsc_sink_caps->branch_overall_throughput_0_mps = 680;
	else {
		dsc_sink_caps->branch_overall_throughput_0_mps *= 50;
		dsc_sink_caps->branch_overall_throughput_0_mps += 600;
	}

	dsc_sink_caps->branch_overall_throughput_1_mps =
		dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_OVERALL_THROUGHPUT_1 - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0];
	if (dsc_sink_caps->branch_overall_throughput_1_mps == 0)
		dsc_sink_caps->branch_overall_throughput_1_mps = 0;
	else if (dsc_sink_caps->branch_overall_throughput_1_mps == 1)
		dsc_sink_caps->branch_overall_throughput_1_mps = 680;
	else {
		dsc_sink_caps->branch_overall_throughput_1_mps *= 50;
		dsc_sink_caps->branch_overall_throughput_1_mps += 600;
	}

	dsc_sink_caps->branch_max_line_width =
		dpcd_dsc_branch_decoder_caps[DP_DSC_BRANCH_MAX_LINE_WIDTH - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0] * 320;
	ASSERT(dsc_sink_caps->branch_max_line_width == 0 || dsc_sink_caps->branch_max_line_width >= 5120);

	dsc_sink_caps->is_dp = true;
	return true;
}


/* If DSC is possbile, get DSC bandwidth range based on [min_bpp, max_bpp] target bitrate range and
 * timing's pixel clock and uncompressed bandwidth.
 * If DSC is not possible, leave '*range' untouched.
 */
bool dc_dsc_compute_bandwidth_range(
		const struct display_stream_compressor *dsc,
		uint32_t dsc_min_slice_height_override,
		uint32_t min_bpp_x16,
		uint32_t max_bpp_x16,
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		const struct dc_crtc_timing *timing,
		struct dc_dsc_bw_range *range)
{
	bool is_dsc_possible = false;
	struct dsc_enc_caps dsc_enc_caps;
	struct dsc_enc_caps dsc_common_caps;
	struct dc_dsc_config config;

	get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);

	is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, &dsc_enc_caps,
			timing->pixel_encoding, &dsc_common_caps);

	if (is_dsc_possible)
		is_dsc_possible = setup_dsc_config(dsc_sink_caps, &dsc_enc_caps, 0, timing,
				dsc_min_slice_height_override, max_bpp_x16, &config);

	if (is_dsc_possible)
		get_dsc_bandwidth_range(min_bpp_x16, max_bpp_x16,
				config.num_slices_h, &dsc_common_caps, timing, range);

	return is_dsc_possible;
}

static void get_dsc_enc_caps(
		const struct display_stream_compressor *dsc,
		struct dsc_enc_caps *dsc_enc_caps,
		int pixel_clock_100Hz)
{
	// This is a static HW query, so we can use any DSC

	memset(dsc_enc_caps, 0, sizeof(struct dsc_enc_caps));
	if (dsc) {
		if (!dsc->ctx->dc->debug.disable_dsc)
			dsc->funcs->dsc_get_enc_caps(dsc_enc_caps, pixel_clock_100Hz);
		if (dsc->ctx->dc->debug.native422_support)
			dsc_enc_caps->color_formats.bits.YCBCR_NATIVE_422 = 1;
	}
}

/* Returns 'false' if no intersection was found for at least one capability.
 * It also implicitly validates some sink caps against invalid value of zero.
 */
static bool intersect_dsc_caps(
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		const struct dsc_enc_caps *dsc_enc_caps,
		enum dc_pixel_encoding pixel_encoding,
		struct dsc_enc_caps *dsc_common_caps)
{
	int32_t max_slices;
	int32_t total_sink_throughput;

	memset(dsc_common_caps, 0, sizeof(struct dsc_enc_caps));

	dsc_common_caps->dsc_version = min(dsc_sink_caps->dsc_version, dsc_enc_caps->dsc_version);
	if (!dsc_common_caps->dsc_version)
		return false;

	dsc_common_caps->slice_caps.bits.NUM_SLICES_1 =
		dsc_sink_caps->slice_caps1.bits.NUM_SLICES_1 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_1;
	dsc_common_caps->slice_caps.bits.NUM_SLICES_2 =
		dsc_sink_caps->slice_caps1.bits.NUM_SLICES_2 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_2;
	dsc_common_caps->slice_caps.bits.NUM_SLICES_4 =
		dsc_sink_caps->slice_caps1.bits.NUM_SLICES_4 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_4;
	dsc_common_caps->slice_caps.bits.NUM_SLICES_8 =
		dsc_sink_caps->slice_caps1.bits.NUM_SLICES_8 && dsc_enc_caps->slice_caps.bits.NUM_SLICES_8;
	if (!dsc_common_caps->slice_caps.raw)
		return false;

	dsc_common_caps->lb_bit_depth = min(dsc_sink_caps->lb_bit_depth, dsc_enc_caps->lb_bit_depth);
	if (!dsc_common_caps->lb_bit_depth)
		return false;

	dsc_common_caps->is_block_pred_supported =
		dsc_sink_caps->is_block_pred_supported && dsc_enc_caps->is_block_pred_supported;

	dsc_common_caps->color_formats.raw = dsc_sink_caps->color_formats.raw & dsc_enc_caps->color_formats.raw;
	if (!dsc_common_caps->color_formats.raw)
		return false;

	dsc_common_caps->color_depth.raw = dsc_sink_caps->color_depth.raw & dsc_enc_caps->color_depth.raw;
	if (!dsc_common_caps->color_depth.raw)
		return false;

	max_slices = 0;
	if (dsc_common_caps->slice_caps.bits.NUM_SLICES_1)
		max_slices = 1;

	if (dsc_common_caps->slice_caps.bits.NUM_SLICES_2)
		max_slices = 2;

	if (dsc_common_caps->slice_caps.bits.NUM_SLICES_4)
		max_slices = 4;

	total_sink_throughput = max_slices * dsc_sink_caps->throughput_mode_0_mps;
	if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
		total_sink_throughput = max_slices * dsc_sink_caps->throughput_mode_1_mps;

	dsc_common_caps->max_total_throughput_mps = min(total_sink_throughput, dsc_enc_caps->max_total_throughput_mps);

	dsc_common_caps->max_slice_width = min(dsc_sink_caps->max_slice_width, dsc_enc_caps->max_slice_width);
	if (!dsc_common_caps->max_slice_width)
		return false;

	dsc_common_caps->bpp_increment_div = min(dsc_sink_caps->bpp_increment_div, dsc_enc_caps->bpp_increment_div);

	// TODO DSC: Remove this workaround for N422 and 420 once it's fixed, or move it to get_dsc_encoder_caps()
	if (pixel_encoding == PIXEL_ENCODING_YCBCR422 || pixel_encoding == PIXEL_ENCODING_YCBCR420)
		dsc_common_caps->bpp_increment_div = min(dsc_common_caps->bpp_increment_div, (uint32_t)8);

	dsc_common_caps->is_dp = dsc_sink_caps->is_dp;
	return true;
}

static inline uint32_t dsc_div_by_10_round_up(uint32_t value)
{
	return (value + 9) / 10;
}

static struct fixed31_32 compute_dsc_max_bandwidth_overhead(
		const struct dc_crtc_timing *timing,
		const int num_slices_h,
		const bool is_dp)
{
	struct fixed31_32 max_dsc_overhead;
	struct fixed31_32 refresh_rate;

	if (dsc_policy_disable_dsc_stream_overhead || !is_dp)
		return dc_fixpt_from_int(0);

	/* use target bpp that can take entire target bandwidth */
	refresh_rate = dc_fixpt_from_int(timing->pix_clk_100hz);
	refresh_rate = dc_fixpt_div_int(refresh_rate, timing->h_total);
	refresh_rate = dc_fixpt_div_int(refresh_rate, timing->v_total);
	refresh_rate = dc_fixpt_mul_int(refresh_rate, 100);

	max_dsc_overhead = dc_fixpt_from_int(num_slices_h);
	max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, timing->v_total);
	max_dsc_overhead = dc_fixpt_mul_int(max_dsc_overhead, 256);
	max_dsc_overhead = dc_fixpt_div_int(max_dsc_overhead, 1000);
	max_dsc_overhead = dc_fixpt_mul(max_dsc_overhead, refresh_rate);

	return max_dsc_overhead;
}

static uint32_t compute_bpp_x16_from_target_bandwidth(
	const uint32_t bandwidth_in_kbps,
	const struct dc_crtc_timing *timing,
	const uint32_t num_slices_h,
	const uint32_t bpp_increment_div,
	const bool is_dp)
{
	struct fixed31_32 overhead_in_kbps;
	struct fixed31_32 effective_bandwidth_in_kbps;
	struct fixed31_32 bpp_x16;

	overhead_in_kbps = compute_dsc_max_bandwidth_overhead(
				timing, num_slices_h, is_dp);
	effective_bandwidth_in_kbps = dc_fixpt_from_int(bandwidth_in_kbps);
	effective_bandwidth_in_kbps = dc_fixpt_sub(effective_bandwidth_in_kbps,
			overhead_in_kbps);
	bpp_x16 = dc_fixpt_mul_int(effective_bandwidth_in_kbps, 10);
	bpp_x16 = dc_fixpt_div_int(bpp_x16, timing->pix_clk_100hz);
	bpp_x16 = dc_fixpt_from_int(dc_fixpt_floor(dc_fixpt_mul_int(bpp_x16, bpp_increment_div)));
	bpp_x16 = dc_fixpt_div_int(bpp_x16, bpp_increment_div);
	bpp_x16 = dc_fixpt_mul_int(bpp_x16, 16);
	return dc_fixpt_floor(bpp_x16);
}

/* Get DSC bandwidth range based on [min_bpp, max_bpp] target bitrate range, and timing's pixel clock
 * and uncompressed bandwidth.
 */
static void get_dsc_bandwidth_range(
		const uint32_t min_bpp_x16,
		const uint32_t max_bpp_x16,
		const uint32_t num_slices_h,
		const struct dsc_enc_caps *dsc_caps,
		const struct dc_crtc_timing *timing,
		struct dc_dsc_bw_range *range)
{
	/* native stream bandwidth */
	range->stream_kbps = dc_bandwidth_in_kbps_from_timing(timing);

	/* max dsc target bpp */
	range->max_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
			max_bpp_x16, num_slices_h, dsc_caps->is_dp);
	range->max_target_bpp_x16 = max_bpp_x16;
	if (range->max_kbps > range->stream_kbps) {
		/* max dsc target bpp is capped to native bandwidth */
		range->max_kbps = range->stream_kbps;
		range->max_target_bpp_x16 = compute_bpp_x16_from_target_bandwidth(
				range->max_kbps, timing, num_slices_h,
				dsc_caps->bpp_increment_div,
				dsc_caps->is_dp);
	}

	/* min dsc target bpp */
	range->min_kbps = dc_dsc_stream_bandwidth_in_kbps(timing,
			min_bpp_x16, num_slices_h, dsc_caps->is_dp);
	range->min_target_bpp_x16 = min_bpp_x16;
	if (range->min_kbps > range->max_kbps) {
		/* min dsc target bpp is capped to max dsc bandwidth*/
		range->min_kbps = range->max_kbps;
		range->min_target_bpp_x16 = range->max_target_bpp_x16;
	}
}

/* Decides if DSC should be used and calculates target bpp if it should, applying DSC policy.
 *
 * Returns:
 *     - 'true' if DSC was required by policy and was successfully applied
 *     - 'false' if DSC was not necessary (e.g. if uncompressed stream fits 'target_bandwidth_kbps'),
 *        or if it couldn't be applied based on DSC policy.
 */
static bool decide_dsc_target_bpp_x16(
		const struct dc_dsc_policy *policy,
		const struct dsc_enc_caps *dsc_common_caps,
		const int target_bandwidth_kbps,
		const struct dc_crtc_timing *timing,
		const int num_slices_h,
		int *target_bpp_x16)
{
	bool should_use_dsc = false;
	struct dc_dsc_bw_range range;

	memset(&range, 0, sizeof(range));

	get_dsc_bandwidth_range(policy->min_target_bpp * 16, policy->max_target_bpp * 16,
			num_slices_h, dsc_common_caps, timing, &range);
	if (!policy->enable_dsc_when_not_needed && target_bandwidth_kbps >= range.stream_kbps) {
		/* enough bandwidth without dsc */
		*target_bpp_x16 = 0;
		should_use_dsc = false;
	} else if (policy->preferred_bpp_x16 > 0 &&
			policy->preferred_bpp_x16 <= range.max_target_bpp_x16 &&
			policy->preferred_bpp_x16 >= range.min_target_bpp_x16) {
		*target_bpp_x16 = policy->preferred_bpp_x16;
		should_use_dsc = true;
	} else if (target_bandwidth_kbps >= range.max_kbps) {
		/* use max target bpp allowed */
		*target_bpp_x16 = range.max_target_bpp_x16;
		should_use_dsc = true;
	} else if (target_bandwidth_kbps >= range.min_kbps) {
		/* use target bpp that can take entire target bandwidth */
		*target_bpp_x16 = compute_bpp_x16_from_target_bandwidth(
				target_bandwidth_kbps, timing, num_slices_h,
				dsc_common_caps->bpp_increment_div,
				dsc_common_caps->is_dp);
		should_use_dsc = true;
	} else {
		/* not enough bandwidth to fulfill minimum requirement */
		*target_bpp_x16 = 0;
		should_use_dsc = false;
	}

	return should_use_dsc;
}

#define MIN_AVAILABLE_SLICES_SIZE  4

static int get_available_dsc_slices(union dsc_enc_slice_caps slice_caps, int *available_slices)
{
	int idx = 0;

	memset(available_slices, -1, MIN_AVAILABLE_SLICES_SIZE);

	if (slice_caps.bits.NUM_SLICES_1)
		available_slices[idx++] = 1;

	if (slice_caps.bits.NUM_SLICES_2)
		available_slices[idx++] = 2;

	if (slice_caps.bits.NUM_SLICES_4)
		available_slices[idx++] = 4;

	if (slice_caps.bits.NUM_SLICES_8)
		available_slices[idx++] = 8;

	return idx;
}


static int get_max_dsc_slices(union dsc_enc_slice_caps slice_caps)
{
	int max_slices = 0;
	int available_slices[MIN_AVAILABLE_SLICES_SIZE];
	int end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);

	if (end_idx > 0)
		max_slices = available_slices[end_idx - 1];

	return max_slices;
}


// Increment sice number in available sice numbers stops if possible, or just increment if not
static int inc_num_slices(union dsc_enc_slice_caps slice_caps, int num_slices)
{
	// Get next bigger num slices available in common caps
	int available_slices[MIN_AVAILABLE_SLICES_SIZE];
	int end_idx;
	int i;
	int new_num_slices = num_slices;

	end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
	if (end_idx == 0) {
		// No available slices found
		new_num_slices++;
		return new_num_slices;
	}

	// Numbers of slices found - get the next bigger number
	for (i = 0; i < end_idx; i++) {
		if (new_num_slices < available_slices[i]) {
			new_num_slices = available_slices[i];
			break;
		}
	}

	if (new_num_slices == num_slices) // No biger number of slices found
		new_num_slices++;

	return new_num_slices;
}


// Decrement sice number in available sice numbers stops if possible, or just decrement if not. Stop at zero.
static int dec_num_slices(union dsc_enc_slice_caps slice_caps, int num_slices)
{
	// Get next bigger num slices available in common caps
	int available_slices[MIN_AVAILABLE_SLICES_SIZE];
	int end_idx;
	int i;
	int new_num_slices = num_slices;

	end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
	if (end_idx == 0 && new_num_slices > 0) {
		// No numbers of slices found
		new_num_slices++;
		return new_num_slices;
	}

	// Numbers of slices found - get the next smaller number
	for (i = end_idx - 1; i >= 0; i--) {
		if (new_num_slices > available_slices[i]) {
			new_num_slices = available_slices[i];
			break;
		}
	}

	if (new_num_slices == num_slices) {
		// No smaller number of slices found
		new_num_slices--;
		if (new_num_slices < 0)
			new_num_slices = 0;
	}

	return new_num_slices;
}


// Choose next bigger number of slices if the requested number of slices is not available
static int fit_num_slices_up(union dsc_enc_slice_caps slice_caps, int num_slices)
{
	// Get next bigger num slices available in common caps
	int available_slices[MIN_AVAILABLE_SLICES_SIZE];
	int end_idx;
	int i;
	int new_num_slices = num_slices;

	end_idx = get_available_dsc_slices(slice_caps, &available_slices[0]);
	if (end_idx == 0) {
		// No available slices found
		new_num_slices++;
		return new_num_slices;
	}

	// Numbers of slices found - get the equal or next bigger number
	for (i = 0; i < end_idx; i++) {
		if (new_num_slices <= available_slices[i]) {
			new_num_slices = available_slices[i];
			break;
		}
	}

	return new_num_slices;
}


/* Attempts to set DSC configuration for the stream, applying DSC policy.
 * Returns 'true' if successful or 'false' if not.
 *
 * Parameters:
 *
 * dsc_sink_caps       - DSC sink decoder capabilities (from DPCD)
 *
 * dsc_enc_caps        - DSC encoder capabilities
 *
 * target_bandwidth_kbps  - Target bandwidth to fit the stream into.
 *                          If 0, do not calculate target bpp.
 *
 * timing              - The stream timing to fit into 'target_bandwidth_kbps' or apply
 *                       maximum compression to, if 'target_badwidth == 0'
 *
 * dsc_cfg             - DSC configuration to use if it was possible to come up with
 *                       one for the given inputs.
 *                       The target bitrate after DSC can be calculated by multiplying
 *                       dsc_cfg.bits_per_pixel (in U6.4 format) by pixel rate, e.g.
 *
 *                       dsc_stream_bitrate_kbps = (int)ceil(timing->pix_clk_khz * dsc_cfg.bits_per_pixel / 16.0);
 */
static bool setup_dsc_config(
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		const struct dsc_enc_caps *dsc_enc_caps,
		int target_bandwidth_kbps,
		const struct dc_crtc_timing *timing,
		int min_slice_height_override,
		int max_dsc_target_bpp_limit_override_x16,
		struct dc_dsc_config *dsc_cfg)
{
	struct dsc_enc_caps dsc_common_caps;
	int max_slices_h;
	int min_slices_h;
	int num_slices_h;
	int pic_width;
	int slice_width;
	int target_bpp;
	int sink_per_slice_throughput_mps;
	int branch_max_throughput_mps = 0;
	bool is_dsc_possible = false;
	int pic_height;
	int slice_height;
	struct dc_dsc_policy policy;

	memset(dsc_cfg, 0, sizeof(struct dc_dsc_config));

	dc_dsc_get_policy_for_timing(timing, max_dsc_target_bpp_limit_override_x16, &policy);
	pic_width = timing->h_addressable + timing->h_border_left + timing->h_border_right;
	pic_height = timing->v_addressable + timing->v_border_top + timing->v_border_bottom;

	if (!dsc_sink_caps->is_dsc_supported)
		goto done;

	if (dsc_sink_caps->branch_max_line_width && dsc_sink_caps->branch_max_line_width < pic_width)
		goto done;

	// Intersect decoder with encoder DSC caps and validate DSC settings
	is_dsc_possible = intersect_dsc_caps(dsc_sink_caps, dsc_enc_caps, timing->pixel_encoding, &dsc_common_caps);
	if (!is_dsc_possible)
		goto done;

	sink_per_slice_throughput_mps = 0;

	// Validate available DSC settings against the mode timing

	// Validate color format (and pick up the throughput values)
	dsc_cfg->ycbcr422_simple = false;
	switch (timing->pixel_encoding)	{
	case PIXEL_ENCODING_RGB:
		is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.RGB;
		sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
		branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_0_mps;
		break;
	case PIXEL_ENCODING_YCBCR444:
		is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_444;
		sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
		branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_0_mps;
		break;
	case PIXEL_ENCODING_YCBCR422:
		is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_NATIVE_422;
		sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_1_mps;
		branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_1_mps;
		if (!is_dsc_possible) {
			is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_SIMPLE_422;
			dsc_cfg->ycbcr422_simple = is_dsc_possible;
			sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_0_mps;
		}
		break;
	case PIXEL_ENCODING_YCBCR420:
		is_dsc_possible = (bool)dsc_common_caps.color_formats.bits.YCBCR_NATIVE_420;
		sink_per_slice_throughput_mps = dsc_sink_caps->throughput_mode_1_mps;
		branch_max_throughput_mps = dsc_sink_caps->branch_overall_throughput_1_mps;
		break;
	default:
		is_dsc_possible = false;
	}

	// Validate branch's maximum throughput
	if (branch_max_throughput_mps && dsc_div_by_10_round_up(timing->pix_clk_100hz) > branch_max_throughput_mps * 1000)
		is_dsc_possible = false;

	if (!is_dsc_possible)
		goto done;

	// Color depth
	switch (timing->display_color_depth) {
	case COLOR_DEPTH_888:
		is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_8_BPC;
		break;
	case COLOR_DEPTH_101010:
		is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_10_BPC;
		break;
	case COLOR_DEPTH_121212:
		is_dsc_possible = (bool)dsc_common_caps.color_depth.bits.COLOR_DEPTH_12_BPC;
		break;
	default:
		is_dsc_possible = false;
	}

	if (!is_dsc_possible)
		goto done;

	// Slice width (i.e. number of slices per line)
	max_slices_h = get_max_dsc_slices(dsc_common_caps.slice_caps);

	while (max_slices_h > 0) {
		if (pic_width % max_slices_h == 0)
			break;

		max_slices_h = dec_num_slices(dsc_common_caps.slice_caps, max_slices_h);
	}

	is_dsc_possible = (dsc_common_caps.max_slice_width > 0);
	if (!is_dsc_possible)
		goto done;

	min_slices_h = pic_width / dsc_common_caps.max_slice_width;
	if (pic_width % dsc_common_caps.max_slice_width)
		min_slices_h++;

	min_slices_h = fit_num_slices_up(dsc_common_caps.slice_caps, min_slices_h);

	while (min_slices_h <= max_slices_h) {
		int pix_clk_per_slice_khz = dsc_div_by_10_round_up(timing->pix_clk_100hz) / min_slices_h;
		if (pix_clk_per_slice_khz <= sink_per_slice_throughput_mps * 1000)
			break;

		min_slices_h = inc_num_slices(dsc_common_caps.slice_caps, min_slices_h);
	}

	if (pic_width % min_slices_h != 0)
		min_slices_h = 0; // DSC TODO: Maybe try increasing the number of slices first?

	is_dsc_possible = (min_slices_h <= max_slices_h);
	if (!is_dsc_possible)
		goto done;

	if (policy.use_min_slices_h) {
		if (min_slices_h > 0)
			num_slices_h = min_slices_h;
		else if (max_slices_h > 0) { // Fall back to max slices if min slices is not working out
			if (policy.max_slices_h)
				num_slices_h = min(policy.max_slices_h, max_slices_h);
			else
				num_slices_h = max_slices_h;
		} else
			is_dsc_possible = false;
	} else {
		if (max_slices_h > 0) {
			if (policy.max_slices_h)
				num_slices_h = min(policy.max_slices_h, max_slices_h);
			else
				num_slices_h = max_slices_h;
		} else if (min_slices_h > 0) // Fall back to min slices if max slices is not possible
			num_slices_h = min_slices_h;
		else
			is_dsc_possible = false;
	}

	if (!is_dsc_possible)
		goto done;

	dsc_cfg->num_slices_h = num_slices_h;
	slice_width = pic_width / num_slices_h;

	is_dsc_possible = slice_width <= dsc_common_caps.max_slice_width;
	if (!is_dsc_possible)
		goto done;

	// Slice height (i.e. number of slices per column): start with policy and pick the first one that height is divisible by.
	// For 4:2:0 make sure the slice height is divisible by 2 as well.
	if (min_slice_height_override == 0)
		slice_height = min(policy.min_slice_height, pic_height);
	else
		slice_height = min(min_slice_height_override, pic_height);

	while (slice_height < pic_height && (pic_height % slice_height != 0 ||
		(timing->pixel_encoding == PIXEL_ENCODING_YCBCR420 && slice_height % 2 != 0)))
		slice_height++;

	if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420) // For the case when pic_height < dsc_policy.min_sice_height
		is_dsc_possible = (slice_height % 2 == 0);

	if (!is_dsc_possible)
		goto done;

	dsc_cfg->num_slices_v = pic_height/slice_height;

	if (target_bandwidth_kbps > 0) {
		is_dsc_possible = decide_dsc_target_bpp_x16(
				&policy,
				&dsc_common_caps,
				target_bandwidth_kbps,
				timing,
				num_slices_h,
				&target_bpp);
		dsc_cfg->bits_per_pixel = target_bpp;
	}
	if (!is_dsc_possible)
		goto done;

	// Final decission: can we do DSC or not?
	if (is_dsc_possible) {
		// Fill out the rest of DSC settings
		dsc_cfg->block_pred_enable = dsc_common_caps.is_block_pred_supported;
		dsc_cfg->linebuf_depth = dsc_common_caps.lb_bit_depth;
		dsc_cfg->version_minor = (dsc_common_caps.dsc_version & 0xf0) >> 4;
		dsc_cfg->is_dp = dsc_sink_caps->is_dp;
	}

done:
	if (!is_dsc_possible)
		memset(dsc_cfg, 0, sizeof(struct dc_dsc_config));

	return is_dsc_possible;
}

bool dc_dsc_compute_config(
		const struct display_stream_compressor *dsc,
		const struct dsc_dec_dpcd_caps *dsc_sink_caps,
		uint32_t dsc_min_slice_height_override,
		uint32_t max_target_bpp_limit_override,
		uint32_t target_bandwidth_kbps,
		const struct dc_crtc_timing *timing,
		struct dc_dsc_config *dsc_cfg)
{
	bool is_dsc_possible = false;
	struct dsc_enc_caps dsc_enc_caps;

	get_dsc_enc_caps(dsc, &dsc_enc_caps, timing->pix_clk_100hz);
	is_dsc_possible = setup_dsc_config(dsc_sink_caps,
		&dsc_enc_caps,
		target_bandwidth_kbps,
		timing, dsc_min_slice_height_override,
		max_target_bpp_limit_override * 16, dsc_cfg);
	return is_dsc_possible;
}

uint32_t dc_dsc_stream_bandwidth_in_kbps(const struct dc_crtc_timing *timing,
	uint32_t bpp_x16, uint32_t num_slices_h, bool is_dp)
{
	struct fixed31_32 overhead_in_kbps;
	struct fixed31_32 bpp;
	struct fixed31_32 actual_bandwidth_in_kbps;

	overhead_in_kbps = compute_dsc_max_bandwidth_overhead(
		timing, num_slices_h, is_dp);
	bpp = dc_fixpt_from_fraction(bpp_x16, 16);
	actual_bandwidth_in_kbps = dc_fixpt_from_fraction(timing->pix_clk_100hz, 10);
	actual_bandwidth_in_kbps = dc_fixpt_mul(actual_bandwidth_in_kbps, bpp);
	actual_bandwidth_in_kbps = dc_fixpt_add(actual_bandwidth_in_kbps, overhead_in_kbps);
	return dc_fixpt_ceil(actual_bandwidth_in_kbps);
}

void dc_dsc_get_policy_for_timing(const struct dc_crtc_timing *timing,
		uint32_t max_target_bpp_limit_override_x16,
		struct dc_dsc_policy *policy)
{
	uint32_t bpc = 0;

	policy->min_target_bpp = 0;
	policy->max_target_bpp = 0;

	/* DSC Policy: Use minimum number of slices that fits the pixel clock */
	policy->use_min_slices_h = true;

	/* DSC Policy: Use max available slices
	 * (in our case 4 for or 8, depending on the mode)
	 */
	policy->max_slices_h = 0;

	/* DSC Policy: Use slice height recommended
	 * by VESA DSC Spreadsheet user guide
	 */
	policy->min_slice_height = 108;

	/* DSC Policy: follow DP specs with an internal upper limit to 16 bpp
	 * for better interoperability
	 */
	switch (timing->display_color_depth) {
	case COLOR_DEPTH_888:
		bpc = 8;
		break;
	case COLOR_DEPTH_101010:
		bpc = 10;
		break;
	case COLOR_DEPTH_121212:
		bpc = 12;
		break;
	default:
		return;
	}
	switch (timing->pixel_encoding) {
	case PIXEL_ENCODING_RGB:
	case PIXEL_ENCODING_YCBCR444:
	case PIXEL_ENCODING_YCBCR422: /* assume no YCbCr422 native support */
		/* DP specs limits to 8 */
		policy->min_target_bpp = 8;
		/* DP specs limits to 3 x bpc */
		policy->max_target_bpp = 3 * bpc;
		break;
	case PIXEL_ENCODING_YCBCR420:
		/* DP specs limits to 6 */
		policy->min_target_bpp = 6;
		/* DP specs limits to 1.5 x bpc assume bpc is an even number */
		policy->max_target_bpp = bpc * 3 / 2;
		break;
	default:
		return;
	}

	policy->preferred_bpp_x16 = timing->dsc_fixed_bits_per_pixel_x16;

	/* internal upper limit, default 16 bpp */
	if (policy->max_target_bpp > dsc_policy_max_target_bpp_limit)
		policy->max_target_bpp = dsc_policy_max_target_bpp_limit;

	/* apply override */
	if (max_target_bpp_limit_override_x16 && policy->max_target_bpp > max_target_bpp_limit_override_x16 / 16)
		policy->max_target_bpp = max_target_bpp_limit_override_x16 / 16;

	/* enable DSC when not needed, default false */
	if (dsc_policy_enable_dsc_when_not_needed)
		policy->enable_dsc_when_not_needed = dsc_policy_enable_dsc_when_not_needed;
	else
		policy->enable_dsc_when_not_needed = false;
}

void dc_dsc_policy_set_max_target_bpp_limit(uint32_t limit)
{
	dsc_policy_max_target_bpp_limit = limit;
}

void dc_dsc_policy_set_enable_dsc_when_not_needed(bool enable)
{
	dsc_policy_enable_dsc_when_not_needed = enable;
}

void dc_dsc_policy_set_disable_dsc_stream_overhead(bool disable)
{
	dsc_policy_disable_dsc_stream_overhead = disable;
}