drivers/gpu/drm/amd/amdgpu/amdgpu_pll.c - linux - Git at Google

 /*
  * Copyright 2014 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.
  *
  */

 #include <drm/amdgpu_drm.h>
 #include "amdgpu.h"
 #include "atom.h"
 #include "atombios_encoders.h"
 #include "amdgpu_pll.h"
 #include <asm/div64.h>
 #include <linux/gcd.h>

 /**
  * amdgpu_pll_reduce_ratio - fractional number reduction
  *
  * @nom: nominator
  * @den: denominator
  * @nom_min: minimum value for nominator
  * @den_min: minimum value for denominator
  *
  * Find the greatest common divisor and apply it on both nominator and
  * denominator, but make nominator and denominator are at least as large
  * as their minimum values.
  */
 static void amdgpu_pll_reduce_ratio(unsigned *nom, unsigned *den,
 				    unsigned nom_min, unsigned den_min)
 {
 	unsigned tmp;

 	/* reduce the numbers to a simpler ratio */
 	tmp = gcd(*nom, *den);
 	*nom /= tmp;
 	*den /= tmp;

 	/* make sure nominator is large enough */
 	if (*nom < nom_min) {
 		tmp = DIV_ROUND_UP(nom_min, *nom);
 		*nom *= tmp;
 		*den *= tmp;
 	}

 	/* make sure the denominator is large enough */
 	if (*den < den_min) {
 		tmp = DIV_ROUND_UP(den_min, *den);
 		*nom *= tmp;
 		*den *= tmp;
 	}
 }

 /**
  * amdgpu_pll_get_fb_ref_div - feedback and ref divider calculation
  *
  * @nom: nominator
  * @den: denominator
  * @post_div: post divider
  * @fb_div_max: feedback divider maximum
  * @ref_div_max: reference divider maximum
  * @fb_div: resulting feedback divider
  * @ref_div: resulting reference divider
  *
  * Calculate feedback and reference divider for a given post divider. Makes
  * sure we stay within the limits.
  */
 static void amdgpu_pll_get_fb_ref_div(struct amdgpu_device *adev, unsigned int nom,
 				      unsigned int den, unsigned int post_div,
 				      unsigned int fb_div_max, unsigned int ref_div_max,
 				      unsigned int *fb_div, unsigned int *ref_div)
 {

 	/* limit reference * post divider to a maximum */
 	if (adev->family == AMDGPU_FAMILY_SI)
 		ref_div_max = min(100 / post_div, ref_div_max);
 	else
 		ref_div_max = min(128 / post_div, ref_div_max);

 	/* get matching reference and feedback divider */
 	*ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
 	*fb_div = DIV_ROUND_CLOSEST(nom * *ref_div * post_div, den);

 	/* limit fb divider to its maximum */
 	if (*fb_div > fb_div_max) {
 		*ref_div = DIV_ROUND_CLOSEST(*ref_div * fb_div_max, *fb_div);
 		*fb_div = fb_div_max;
 	}
 }

 /**
  * amdgpu_pll_compute - compute PLL paramaters
  *
  * @pll: information about the PLL
  * @freq: requested frequency
  * @dot_clock_p: resulting pixel clock
  * @fb_div_p: resulting feedback divider
  * @frac_fb_div_p: fractional part of the feedback divider
  * @ref_div_p: resulting reference divider
  * @post_div_p: resulting reference divider
  *
  * Try to calculate the PLL parameters to generate the given frequency:
  * dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
  */
 void amdgpu_pll_compute(struct amdgpu_device *adev,
 			struct amdgpu_pll *pll,
 			u32 freq,
 			u32 *dot_clock_p,
 			u32 *fb_div_p,
 			u32 *frac_fb_div_p,
 			u32 *ref_div_p,
 			u32 *post_div_p)
 {
 	unsigned target_clock = pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV ?
 		freq : freq / 10;

 	unsigned fb_div_min, fb_div_max, fb_div;
 	unsigned post_div_min, post_div_max, post_div;
 	unsigned ref_div_min, ref_div_max, ref_div;
 	unsigned post_div_best, diff_best;
 	unsigned nom, den;

 	/* determine allowed feedback divider range */
 	fb_div_min = pll->min_feedback_div;
 	fb_div_max = pll->max_feedback_div;

 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 		fb_div_min *= 10;
 		fb_div_max *= 10;
 	}

 	/* determine allowed ref divider range */
 	if (pll->flags & AMDGPU_PLL_USE_REF_DIV)
 		ref_div_min = pll->reference_div;
 	else
 		ref_div_min = pll->min_ref_div;

 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV &&
 	    pll->flags & AMDGPU_PLL_USE_REF_DIV)
 		ref_div_max = pll->reference_div;
 	else
 		ref_div_max = pll->max_ref_div;

 	/* determine allowed post divider range */
 	if (pll->flags & AMDGPU_PLL_USE_POST_DIV) {
 		post_div_min = pll->post_div;
 		post_div_max = pll->post_div;
 	} else {
 		unsigned vco_min, vco_max;

 		if (pll->flags & AMDGPU_PLL_IS_LCD) {
 			vco_min = pll->lcd_pll_out_min;
 			vco_max = pll->lcd_pll_out_max;
 		} else {
 			vco_min = pll->pll_out_min;
 			vco_max = pll->pll_out_max;
 		}

 		if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 			vco_min *= 10;
 			vco_max *= 10;
 		}

 		post_div_min = vco_min / target_clock;
 		if ((target_clock * post_div_min) < vco_min)
 			++post_div_min;
 		if (post_div_min < pll->min_post_div)
 			post_div_min = pll->min_post_div;

 		post_div_max = vco_max / target_clock;
 		if ((target_clock * post_div_max) > vco_max)
 			--post_div_max;
 		if (post_div_max > pll->max_post_div)
 			post_div_max = pll->max_post_div;
 	}

 	/* represent the searched ratio as fractional number */
 	nom = target_clock;
 	den = pll->reference_freq;

 	/* reduce the numbers to a simpler ratio */
 	amdgpu_pll_reduce_ratio(&nom, &den, fb_div_min, post_div_min);

 	/* now search for a post divider */
 	if (pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP)
 		post_div_best = post_div_min;
 	else
 		post_div_best = post_div_max;
 	diff_best = ~0;

 	for (post_div = post_div_min; post_div <= post_div_max; ++post_div) {
 		unsigned diff;
 		amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max,
 					  ref_div_max, &fb_div, &ref_div);
 		diff = abs(target_clock - (pll->reference_freq * fb_div) /
 			(ref_div * post_div));

 		if (diff < diff_best || (diff == diff_best &&
 		    !(pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP))) {

 			post_div_best = post_div;
 			diff_best = diff;
 		}
 	}
 	post_div = post_div_best;

 	/* get the feedback and reference divider for the optimal value */
 	amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max, ref_div_max,
 				  &fb_div, &ref_div);

 	/* reduce the numbers to a simpler ratio once more */
 	/* this also makes sure that the reference divider is large enough */
 	amdgpu_pll_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);

 	/* avoid high jitter with small fractional dividers */
 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
 		fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
 		if (fb_div < fb_div_min) {
 			unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
 			fb_div *= tmp;
 			ref_div *= tmp;
 		}
 	}

 	/* and finally save the result */
 	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
 		*fb_div_p = fb_div / 10;
 		*frac_fb_div_p = fb_div % 10;
 	} else {
 		*fb_div_p = fb_div;
 		*frac_fb_div_p = 0;
 	}

 	*dot_clock_p = ((pll->reference_freq * *fb_div_p * 10) +
 			(pll->reference_freq * *frac_fb_div_p)) /
 		       (ref_div * post_div * 10);
 	*ref_div_p = ref_div;
 	*post_div_p = post_div;

 	DRM_DEBUG_KMS("%d - %d, pll dividers - fb: %d.%d ref: %d, post %d\n",
 		      freq, *dot_clock_p * 10, *fb_div_p, *frac_fb_div_p,
 		      ref_div, post_div);
 }

 /**
  * amdgpu_pll_get_use_mask - look up a mask of which pplls are in use
  *
  * @crtc: drm crtc
  *
  * Returns the mask of which PPLLs (Pixel PLLs) are in use.
  */
 u32 amdgpu_pll_get_use_mask(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_crtc *test_crtc;
 	struct amdgpu_crtc *test_amdgpu_crtc;
 	u32 pll_in_use = 0;

 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 		if (crtc == test_crtc)
 			continue;

 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 		if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 			pll_in_use |= (1 << test_amdgpu_crtc->pll_id);
 	}
 	return pll_in_use;
 }

 /**
  * amdgpu_pll_get_shared_dp_ppll - return the PPLL used by another crtc for DP
  *
  * @crtc: drm crtc
  *
  * Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
  * also in DP mode.  For DP, a single PPLL can be used for all DP
  * crtcs/encoders.
  */
 int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_crtc *test_crtc;
 	struct amdgpu_crtc *test_amdgpu_crtc;

 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 		if (crtc == test_crtc)
 			continue;
 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 		if (test_amdgpu_crtc->encoder &&
 		    ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
 			/* for DP use the same PLL for all */
 			if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 				return test_amdgpu_crtc->pll_id;
 		}
 	}
 	return ATOM_PPLL_INVALID;
 }

 /**
  * amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
  *
  * @crtc: drm crtc
  *
  * Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
  * be shared (i.e., same clock).
  */
 int amdgpu_pll_get_shared_nondp_ppll(struct drm_crtc *crtc)
 {
 	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
 	struct drm_device *dev = crtc->dev;
 	struct drm_crtc *test_crtc;
 	struct amdgpu_crtc *test_amdgpu_crtc;
 	u32 adjusted_clock, test_adjusted_clock;

 	adjusted_clock = amdgpu_crtc->adjusted_clock;

 	if (adjusted_clock == 0)
 		return ATOM_PPLL_INVALID;

 	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
 		if (crtc == test_crtc)
 			continue;
 		test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
 		if (test_amdgpu_crtc->encoder &&
 		    !ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
 			/* check if we are already driving this connector with another crtc */
 			if (test_amdgpu_crtc->connector == amdgpu_crtc->connector) {
 				/* if we are, return that pll */
 				if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
 					return test_amdgpu_crtc->pll_id;
 			}
 			/* for non-DP check the clock */
 			test_adjusted_clock = test_amdgpu_crtc->adjusted_clock;
 			if ((crtc->mode.clock == test_crtc->mode.clock) &&
 			    (adjusted_clock == test_adjusted_clock) &&
 			    (amdgpu_crtc->ss_enabled == test_amdgpu_crtc->ss_enabled) &&
 			    (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID))
 				return test_amdgpu_crtc->pll_id;
 		}
 	}
 	return ATOM_PPLL_INVALID;
 }
	/*
	* Copyright 2014 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.
	*
	*/

	#include <drm/amdgpu_drm.h>
	#include "amdgpu.h"
	#include "atom.h"
	#include "atombios_encoders.h"
	#include "amdgpu_pll.h"
	#include <asm/div64.h>
	#include <linux/gcd.h>

	/**
	* amdgpu_pll_reduce_ratio - fractional number reduction
	*
	* @nom: nominator
	* @den: denominator
	* @nom_min: minimum value for nominator
	* @den_min: minimum value for denominator
	*
	* Find the greatest common divisor and apply it on both nominator and
	* denominator, but make nominator and denominator are at least as large
	* as their minimum values.
	*/
	static void amdgpu_pll_reduce_ratio(unsigned nom, unsigned den,
	unsigned nom_min, unsigned den_min)
	{
	unsigned tmp;

	/* reduce the numbers to a simpler ratio */
	tmp = gcd(nom, den);
	*nom /= tmp;
	*den /= tmp;

	/* make sure nominator is large enough */
	if (*nom < nom_min) {
	tmp = DIV_ROUND_UP(nom_min, *nom);
	nom = tmp;
	den = tmp;
	}

	/* make sure the denominator is large enough */
	if (*den < den_min) {
	tmp = DIV_ROUND_UP(den_min, *den);
	nom = tmp;
	den = tmp;
	}
	}

	/**
	* amdgpu_pll_get_fb_ref_div - feedback and ref divider calculation
	*
	* @nom: nominator
	* @den: denominator
	* @post_div: post divider
	* @fb_div_max: feedback divider maximum
	* @ref_div_max: reference divider maximum
	* @fb_div: resulting feedback divider
	* @ref_div: resulting reference divider
	*
	* Calculate feedback and reference divider for a given post divider. Makes
	* sure we stay within the limits.
	*/
	static void amdgpu_pll_get_fb_ref_div(struct amdgpu_device *adev, unsigned int nom,
	unsigned int den, unsigned int post_div,
	unsigned int fb_div_max, unsigned int ref_div_max,
	unsigned int fb_div, unsigned int ref_div)
	{

	/* limit reference * post divider to a maximum */
	if (adev->family == AMDGPU_FAMILY_SI)
	ref_div_max = min(100 / post_div, ref_div_max);
	else
	ref_div_max = min(128 / post_div, ref_div_max);

	/* get matching reference and feedback divider */
	*ref_div = min(max(DIV_ROUND_CLOSEST(den, post_div), 1u), ref_div_max);
	fb_div = DIV_ROUND_CLOSEST(nom ref_div post_div, den);

	/* limit fb divider to its maximum */
	if (*fb_div > fb_div_max) {
	ref_div = DIV_ROUND_CLOSEST(ref_div * fb_div_max, *fb_div);
	*fb_div = fb_div_max;
	}
	}

	/**
	* amdgpu_pll_compute - compute PLL paramaters
	*
	* @pll: information about the PLL
	* @freq: requested frequency
	* @dot_clock_p: resulting pixel clock
	* @fb_div_p: resulting feedback divider
	* @frac_fb_div_p: fractional part of the feedback divider
	* @ref_div_p: resulting reference divider
	* @post_div_p: resulting reference divider
	*
	* Try to calculate the PLL parameters to generate the given frequency:
	* dot_clock = (ref_freq * feedback_div) / (ref_div * post_div)
	*/
	void amdgpu_pll_compute(struct amdgpu_device *adev,
	struct amdgpu_pll *pll,
	u32 freq,
	u32 *dot_clock_p,
	u32 *fb_div_p,
	u32 *frac_fb_div_p,
	u32 *ref_div_p,
	u32 *post_div_p)
	{
	unsigned target_clock = pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV ?
	freq : freq / 10;

	unsigned fb_div_min, fb_div_max, fb_div;
	unsigned post_div_min, post_div_max, post_div;
	unsigned ref_div_min, ref_div_max, ref_div;
	unsigned post_div_best, diff_best;
	unsigned nom, den;

	/* determine allowed feedback divider range */
	fb_div_min = pll->min_feedback_div;
	fb_div_max = pll->max_feedback_div;

	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
	fb_div_min *= 10;
	fb_div_max *= 10;
	}

	/* determine allowed ref divider range */
	if (pll->flags & AMDGPU_PLL_USE_REF_DIV)
	ref_div_min = pll->reference_div;
	else
	ref_div_min = pll->min_ref_div;

	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV &&
	pll->flags & AMDGPU_PLL_USE_REF_DIV)
	ref_div_max = pll->reference_div;
	else
	ref_div_max = pll->max_ref_div;

	/* determine allowed post divider range */
	if (pll->flags & AMDGPU_PLL_USE_POST_DIV) {
	post_div_min = pll->post_div;
	post_div_max = pll->post_div;
	} else {
	unsigned vco_min, vco_max;

	if (pll->flags & AMDGPU_PLL_IS_LCD) {
	vco_min = pll->lcd_pll_out_min;
	vco_max = pll->lcd_pll_out_max;
	} else {
	vco_min = pll->pll_out_min;
	vco_max = pll->pll_out_max;
	}

	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
	vco_min *= 10;
	vco_max *= 10;
	}

	post_div_min = vco_min / target_clock;
	if ((target_clock * post_div_min) < vco_min)
	++post_div_min;
	if (post_div_min < pll->min_post_div)
	post_div_min = pll->min_post_div;

	post_div_max = vco_max / target_clock;
	if ((target_clock * post_div_max) > vco_max)
	--post_div_max;
	if (post_div_max > pll->max_post_div)
	post_div_max = pll->max_post_div;
	}

	/* represent the searched ratio as fractional number */
	nom = target_clock;
	den = pll->reference_freq;

	/* reduce the numbers to a simpler ratio */
	amdgpu_pll_reduce_ratio(&nom, &den, fb_div_min, post_div_min);

	/* now search for a post divider */
	if (pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP)
	post_div_best = post_div_min;
	else
	post_div_best = post_div_max;
	diff_best = ~0;

	for (post_div = post_div_min; post_div <= post_div_max; ++post_div) {
	unsigned diff;
	amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max,
	ref_div_max, &fb_div, &ref_div);
	diff = abs(target_clock - (pll->reference_freq * fb_div) /
	(ref_div * post_div));

	if (diff < diff_best \|\| (diff == diff_best &&
	!(pll->flags & AMDGPU_PLL_PREFER_MINM_OVER_MAXP))) {

	post_div_best = post_div;
	diff_best = diff;
	}
	}
	post_div = post_div_best;

	/* get the feedback and reference divider for the optimal value */
	amdgpu_pll_get_fb_ref_div(adev, nom, den, post_div, fb_div_max, ref_div_max,
	&fb_div, &ref_div);

	/* reduce the numbers to a simpler ratio once more */
	/* this also makes sure that the reference divider is large enough */
	amdgpu_pll_reduce_ratio(&fb_div, &ref_div, fb_div_min, ref_div_min);

	/* avoid high jitter with small fractional dividers */
	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV && (fb_div % 10)) {
	fb_div_min = max(fb_div_min, (9 - (fb_div % 10)) * 20 + 60);
	if (fb_div < fb_div_min) {
	unsigned tmp = DIV_ROUND_UP(fb_div_min, fb_div);
	fb_div *= tmp;
	ref_div *= tmp;
	}
	}

	/* and finally save the result */
	if (pll->flags & AMDGPU_PLL_USE_FRAC_FB_DIV) {
	*fb_div_p = fb_div / 10;
	*frac_fb_div_p = fb_div % 10;
	} else {
	*fb_div_p = fb_div;
	*frac_fb_div_p = 0;
	}

	dot_clock_p = ((pll->reference_freq fb_div_p 10) +
	(pll->reference_freq * *frac_fb_div_p)) /
	(ref_div * post_div * 10);
	*ref_div_p = ref_div;
	*post_div_p = post_div;

	DRM_DEBUG_KMS("%d - %d, pll dividers - fb: %d.%d ref: %d, post %d\n",
	freq, dot_clock_p 10, fb_div_p, frac_fb_div_p,
	ref_div, post_div);
	}

	/**
	* amdgpu_pll_get_use_mask - look up a mask of which pplls are in use
	*
	* @crtc: drm crtc
	*
	* Returns the mask of which PPLLs (Pixel PLLs) are in use.
	*/
	u32 amdgpu_pll_get_use_mask(struct drm_crtc *crtc)
	{
	struct drm_device *dev = crtc->dev;
	struct drm_crtc *test_crtc;
	struct amdgpu_crtc *test_amdgpu_crtc;
	u32 pll_in_use = 0;

	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
	if (crtc == test_crtc)
	continue;

	test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
	if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
	pll_in_use \|= (1 << test_amdgpu_crtc->pll_id);
	}
	return pll_in_use;
	}

	/**
	* amdgpu_pll_get_shared_dp_ppll - return the PPLL used by another crtc for DP
	*
	* @crtc: drm crtc
	*
	* Returns the PPLL (Pixel PLL) used by another crtc/encoder which is
	* also in DP mode. For DP, a single PPLL can be used for all DP
	* crtcs/encoders.
	*/
	int amdgpu_pll_get_shared_dp_ppll(struct drm_crtc *crtc)
	{
	struct drm_device *dev = crtc->dev;
	struct drm_crtc *test_crtc;
	struct amdgpu_crtc *test_amdgpu_crtc;

	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
	if (crtc == test_crtc)
	continue;
	test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
	if (test_amdgpu_crtc->encoder &&
	ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
	/* for DP use the same PLL for all */
	if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
	return test_amdgpu_crtc->pll_id;
	}
	}
	return ATOM_PPLL_INVALID;
	}

	/**
	* amdgpu_pll_get_shared_nondp_ppll - return the PPLL used by another non-DP crtc
	*
	* @crtc: drm crtc
	*
	* Returns the PPLL (Pixel PLL) used by another non-DP crtc/encoder which can
	* be shared (i.e., same clock).
	*/
	int amdgpu_pll_get_shared_nondp_ppll(struct drm_crtc *crtc)
	{
	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
	struct drm_device *dev = crtc->dev;
	struct drm_crtc *test_crtc;
	struct amdgpu_crtc *test_amdgpu_crtc;
	u32 adjusted_clock, test_adjusted_clock;

	adjusted_clock = amdgpu_crtc->adjusted_clock;

	if (adjusted_clock == 0)
	return ATOM_PPLL_INVALID;

	list_for_each_entry(test_crtc, &dev->mode_config.crtc_list, head) {
	if (crtc == test_crtc)
	continue;
	test_amdgpu_crtc = to_amdgpu_crtc(test_crtc);
	if (test_amdgpu_crtc->encoder &&
	!ENCODER_MODE_IS_DP(amdgpu_atombios_encoder_get_encoder_mode(test_amdgpu_crtc->encoder))) {
	/* check if we are already driving this connector with another crtc */
	if (test_amdgpu_crtc->connector == amdgpu_crtc->connector) {
	/* if we are, return that pll */
	if (test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID)
	return test_amdgpu_crtc->pll_id;
	}
	/* for non-DP check the clock */
	test_adjusted_clock = test_amdgpu_crtc->adjusted_clock;
	if ((crtc->mode.clock == test_crtc->mode.clock) &&
	(adjusted_clock == test_adjusted_clock) &&
	(amdgpu_crtc->ss_enabled == test_amdgpu_crtc->ss_enabled) &&
	(test_amdgpu_crtc->pll_id != ATOM_PPLL_INVALID))
	return test_amdgpu_crtc->pll_id;
	}
	}
	return ATOM_PPLL_INVALID;
	}