drivers/gpu/drm/i915/intel_fifo_underrun.c - linux - Git at Google

 /*
  * Copyright © 2014 Intel Corporation
  *
  * 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 (including the next
  * paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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.
  *
  * Authors:
  *    Daniel Vetter <daniel.vetter@ffwll.ch>
  *
  */

 #include "i915_drv.h"
 #include "intel_drv.h"

 /**
  * DOC: fifo underrun handling
  *
  * The i915 driver checks for display fifo underruns using the interrupt signals
  * provided by the hardware. This is enabled by default and fairly useful to
  * debug display issues, especially watermark settings.
  *
  * If an underrun is detected this is logged into dmesg. To avoid flooding logs
  * and occupying the cpu underrun interrupts are disabled after the first
  * occurrence until the next modeset on a given pipe.
  *
  * Note that underrun detection on gmch platforms is a bit more ugly since there
  * is no interrupt (despite that the signalling bit is in the PIPESTAT pipe
  * interrupt register). Also on some other platforms underrun interrupts are
  * shared, which means that if we detect an underrun we need to disable underrun
  * reporting on all pipes.
  *
  * The code also supports underrun detection on the PCH transcoder.
  */

 static bool ivb_can_enable_err_int(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_crtc *crtc;
 	enum pipe pipe;

 	lockdep_assert_held(&dev_priv->irq_lock);

 	for_each_pipe(dev_priv, pipe) {
 		crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

 		if (crtc->cpu_fifo_underrun_disabled)
 			return false;
 	}

 	return true;
 }

 static bool cpt_can_enable_serr_int(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	enum pipe pipe;
 	struct intel_crtc *crtc;

 	lockdep_assert_held(&dev_priv->irq_lock);

 	for_each_pipe(dev_priv, pipe) {
 		crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

 		if (crtc->pch_fifo_underrun_disabled)
 			return false;
 	}

 	return true;
 }

 static void i9xx_check_fifo_underruns(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	i915_reg_t reg = PIPESTAT(crtc->pipe);
 	u32 pipestat = I915_READ(reg) & 0xffff0000;

 	lockdep_assert_held(&dev_priv->irq_lock);

 	if ((pipestat & PIPE_FIFO_UNDERRUN_STATUS) == 0)
 		return;

 	I915_WRITE(reg, pipestat | PIPE_FIFO_UNDERRUN_STATUS);
 	POSTING_READ(reg);

 	trace_intel_cpu_fifo_underrun(dev_priv, crtc->pipe);
 	DRM_ERROR("pipe %c underrun\n", pipe_name(crtc->pipe));
 }

 static void i9xx_set_fifo_underrun_reporting(struct drm_device *dev,
 					     enum pipe pipe,
 					     bool enable, bool old)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	i915_reg_t reg = PIPESTAT(pipe);
 	u32 pipestat = I915_READ(reg) & 0xffff0000;

 	lockdep_assert_held(&dev_priv->irq_lock);

 	if (enable) {
 		I915_WRITE(reg, pipestat | PIPE_FIFO_UNDERRUN_STATUS);
 		POSTING_READ(reg);
 	} else {
 		if (old && pipestat & PIPE_FIFO_UNDERRUN_STATUS)
 			DRM_ERROR("pipe %c underrun\n", pipe_name(pipe));
 	}
 }

 static void ironlake_set_fifo_underrun_reporting(struct drm_device *dev,
 						 enum pipe pipe, bool enable)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	uint32_t bit = (pipe == PIPE_A) ? DE_PIPEA_FIFO_UNDERRUN :
 					  DE_PIPEB_FIFO_UNDERRUN;

 	if (enable)
 		ilk_enable_display_irq(dev_priv, bit);
 	else
 		ilk_disable_display_irq(dev_priv, bit);
 }

 static void ivybridge_check_fifo_underruns(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum pipe pipe = crtc->pipe;
 	uint32_t err_int = I915_READ(GEN7_ERR_INT);

 	lockdep_assert_held(&dev_priv->irq_lock);

 	if ((err_int & ERR_INT_FIFO_UNDERRUN(pipe)) == 0)
 		return;

 	I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));
 	POSTING_READ(GEN7_ERR_INT);

 	trace_intel_cpu_fifo_underrun(dev_priv, pipe);
 	DRM_ERROR("fifo underrun on pipe %c\n", pipe_name(pipe));
 }

 static void ivybridge_set_fifo_underrun_reporting(struct drm_device *dev,
 						  enum pipe pipe,
 						  bool enable, bool old)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	if (enable) {
 		I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));

 		if (!ivb_can_enable_err_int(dev))
 			return;

 		ilk_enable_display_irq(dev_priv, DE_ERR_INT_IVB);
 	} else {
 		ilk_disable_display_irq(dev_priv, DE_ERR_INT_IVB);

 		if (old &&
 		    I915_READ(GEN7_ERR_INT) & ERR_INT_FIFO_UNDERRUN(pipe)) {
 			DRM_ERROR("uncleared fifo underrun on pipe %c\n",
 				  pipe_name(pipe));
 		}
 	}
 }

 static void broadwell_set_fifo_underrun_reporting(struct drm_device *dev,
 						  enum pipe pipe, bool enable)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);

 	if (enable)
 		bdw_enable_pipe_irq(dev_priv, pipe, GEN8_PIPE_FIFO_UNDERRUN);
 	else
 		bdw_disable_pipe_irq(dev_priv, pipe, GEN8_PIPE_FIFO_UNDERRUN);
 }

 static void ibx_set_fifo_underrun_reporting(struct drm_device *dev,
 					    enum transcoder pch_transcoder,
 					    bool enable)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	uint32_t bit = (pch_transcoder == TRANSCODER_A) ?
 		       SDE_TRANSA_FIFO_UNDER : SDE_TRANSB_FIFO_UNDER;

 	if (enable)
 		ibx_enable_display_interrupt(dev_priv, bit);
 	else
 		ibx_disable_display_interrupt(dev_priv, bit);
 }

 static void cpt_check_pch_fifo_underruns(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum transcoder pch_transcoder = (enum transcoder) crtc->pipe;
 	uint32_t serr_int = I915_READ(SERR_INT);

 	lockdep_assert_held(&dev_priv->irq_lock);

 	if ((serr_int & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) == 0)
 		return;

 	I915_WRITE(SERR_INT, SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));
 	POSTING_READ(SERR_INT);

 	trace_intel_pch_fifo_underrun(dev_priv, pch_transcoder);
 	DRM_ERROR("pch fifo underrun on pch transcoder %s\n",
 		  transcoder_name(pch_transcoder));
 }

 static void cpt_set_fifo_underrun_reporting(struct drm_device *dev,
 					    enum transcoder pch_transcoder,
 					    bool enable, bool old)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);

 	if (enable) {
 		I915_WRITE(SERR_INT,
 			   SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));

 		if (!cpt_can_enable_serr_int(dev))
 			return;

 		ibx_enable_display_interrupt(dev_priv, SDE_ERROR_CPT);
 	} else {
 		ibx_disable_display_interrupt(dev_priv, SDE_ERROR_CPT);

 		if (old && I915_READ(SERR_INT) &
 		    SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) {
 			DRM_ERROR("uncleared pch fifo underrun on pch transcoder %s\n",
 				  transcoder_name(pch_transcoder));
 		}
 	}
 }

 static bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
 						    enum pipe pipe, bool enable)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
 	bool old;

 	lockdep_assert_held(&dev_priv->irq_lock);

 	old = !crtc->cpu_fifo_underrun_disabled;
 	crtc->cpu_fifo_underrun_disabled = !enable;

 	if (HAS_GMCH_DISPLAY(dev_priv))
 		i9xx_set_fifo_underrun_reporting(dev, pipe, enable, old);
 	else if (IS_GEN5(dev_priv) || IS_GEN6(dev_priv))
 		ironlake_set_fifo_underrun_reporting(dev, pipe, enable);
 	else if (IS_GEN7(dev_priv))
 		ivybridge_set_fifo_underrun_reporting(dev, pipe, enable, old);
 	else if (INTEL_GEN(dev_priv) >= 8)
 		broadwell_set_fifo_underrun_reporting(dev, pipe, enable);

 	return old;
 }

 /**
  * intel_set_cpu_fifo_underrun_reporting - set cpu fifo underrrun reporting state
  * @dev_priv: i915 device instance
  * @pipe: (CPU) pipe to set state for
  * @enable: whether underruns should be reported or not
  *
  * This function sets the fifo underrun state for @pipe. It is used in the
  * modeset code to avoid false positives since on many platforms underruns are
  * expected when disabling or enabling the pipe.
  *
  * Notice that on some platforms disabling underrun reports for one pipe
  * disables for all due to shared interrupts. Actual reporting is still per-pipe
  * though.
  *
  * Returns the previous state of underrun reporting.
  */
 bool intel_set_cpu_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
 					   enum pipe pipe, bool enable)
 {
 	unsigned long flags;
 	bool ret;

 	spin_lock_irqsave(&dev_priv->irq_lock, flags);
 	ret = __intel_set_cpu_fifo_underrun_reporting(&dev_priv->drm, pipe,
 						      enable);
 	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

 	return ret;
 }

 /**
  * intel_set_pch_fifo_underrun_reporting - set PCH fifo underrun reporting state
  * @dev_priv: i915 device instance
  * @pch_transcoder: the PCH transcoder (same as pipe on IVB and older)
  * @enable: whether underruns should be reported or not
  *
  * This function makes us disable or enable PCH fifo underruns for a specific
  * PCH transcoder. Notice that on some PCHs (e.g. CPT/PPT), disabling FIFO
  * underrun reporting for one transcoder may also disable all the other PCH
  * error interruts for the other transcoders, due to the fact that there's just
  * one interrupt mask/enable bit for all the transcoders.
  *
  * Returns the previous state of underrun reporting.
  */
 bool intel_set_pch_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
 					   enum transcoder pch_transcoder,
 					   bool enable)
 {
 	struct intel_crtc *crtc =
 		intel_get_crtc_for_pipe(dev_priv, (enum pipe) pch_transcoder);
 	unsigned long flags;
 	bool old;

 	/*
 	 * NOTE: Pre-LPT has a fixed cpu pipe -> pch transcoder mapping, but LPT
 	 * has only one pch transcoder A that all pipes can use. To avoid racy
 	 * pch transcoder -> pipe lookups from interrupt code simply store the
 	 * underrun statistics in crtc A. Since we never expose this anywhere
 	 * nor use it outside of the fifo underrun code here using the "wrong"
 	 * crtc on LPT won't cause issues.
 	 */

 	spin_lock_irqsave(&dev_priv->irq_lock, flags);

 	old = !crtc->pch_fifo_underrun_disabled;
 	crtc->pch_fifo_underrun_disabled = !enable;

 	if (HAS_PCH_IBX(dev_priv))
 		ibx_set_fifo_underrun_reporting(&dev_priv->drm,
 						pch_transcoder,
 						enable);
 	else
 		cpt_set_fifo_underrun_reporting(&dev_priv->drm,
 						pch_transcoder,
 						enable, old);

 	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
 	return old;
 }

 /**
  * intel_cpu_fifo_underrun_irq_handler - handle CPU fifo underrun interrupt
  * @dev_priv: i915 device instance
  * @pipe: (CPU) pipe to set state for
  *
  * This handles a CPU fifo underrun interrupt, generating an underrun warning
  * into dmesg if underrun reporting is enabled and then disables the underrun
  * interrupt to avoid an irq storm.
  */
 void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
 					 enum pipe pipe)
 {
 	struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

 	/* We may be called too early in init, thanks BIOS! */
 	if (crtc == NULL)
 		return;

 	/* GMCH can't disable fifo underruns, filter them. */
 	if (HAS_GMCH_DISPLAY(dev_priv) &&
 	    crtc->cpu_fifo_underrun_disabled)
 		return;

 	if (intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false)) {
 		trace_intel_cpu_fifo_underrun(dev_priv, pipe);
 		DRM_ERROR("CPU pipe %c FIFO underrun\n",
 			  pipe_name(pipe));
 	}

 	intel_fbc_handle_fifo_underrun_irq(dev_priv);
 }

 /**
  * intel_pch_fifo_underrun_irq_handler - handle PCH fifo underrun interrupt
  * @dev_priv: i915 device instance
  * @pch_transcoder: the PCH transcoder (same as pipe on IVB and older)
  *
  * This handles a PCH fifo underrun interrupt, generating an underrun warning
  * into dmesg if underrun reporting is enabled and then disables the underrun
  * interrupt to avoid an irq storm.
  */
 void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
 					 enum transcoder pch_transcoder)
 {
 	if (intel_set_pch_fifo_underrun_reporting(dev_priv, pch_transcoder,
 						  false)) {
 		trace_intel_pch_fifo_underrun(dev_priv, pch_transcoder);
 		DRM_ERROR("PCH transcoder %s FIFO underrun\n",
 			  transcoder_name(pch_transcoder));
 	}
 }

 /**
  * intel_check_cpu_fifo_underruns - check for CPU fifo underruns immediately
  * @dev_priv: i915 device instance
  *
  * Check for CPU fifo underruns immediately. Useful on IVB/HSW where the shared
  * error interrupt may have been disabled, and so CPU fifo underruns won't
  * necessarily raise an interrupt, and on GMCH platforms where underruns never
  * raise an interrupt.
  */
 void intel_check_cpu_fifo_underruns(struct drm_i915_private *dev_priv)
 {
 	struct intel_crtc *crtc;

 	spin_lock_irq(&dev_priv->irq_lock);

 	for_each_intel_crtc(&dev_priv->drm, crtc) {
 		if (crtc->cpu_fifo_underrun_disabled)
 			continue;

 		if (HAS_GMCH_DISPLAY(dev_priv))
 			i9xx_check_fifo_underruns(crtc);
 		else if (IS_GEN7(dev_priv))
 			ivybridge_check_fifo_underruns(crtc);
 	}

 	spin_unlock_irq(&dev_priv->irq_lock);
 }

 /**
  * intel_check_pch_fifo_underruns - check for PCH fifo underruns immediately
  * @dev_priv: i915 device instance
  *
  * Check for PCH fifo underruns immediately. Useful on CPT/PPT where the shared
  * error interrupt may have been disabled, and so PCH fifo underruns won't
  * necessarily raise an interrupt.
  */
 void intel_check_pch_fifo_underruns(struct drm_i915_private *dev_priv)
 {
 	struct intel_crtc *crtc;

 	spin_lock_irq(&dev_priv->irq_lock);

 	for_each_intel_crtc(&dev_priv->drm, crtc) {
 		if (crtc->pch_fifo_underrun_disabled)
 			continue;

 		if (HAS_PCH_CPT(dev_priv))
 			cpt_check_pch_fifo_underruns(crtc);
 	}

 	spin_unlock_irq(&dev_priv->irq_lock);
 }
	/*
	* Copyright © 2014 Intel Corporation
	*
	* 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 (including the next
	* paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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.
	*
	* Authors:
	* Daniel Vetter <daniel.vetter@ffwll.ch>
	*
	*/

	#include "i915_drv.h"
	#include "intel_drv.h"

	/**
	* DOC: fifo underrun handling
	*
	* The i915 driver checks for display fifo underruns using the interrupt signals
	* provided by the hardware. This is enabled by default and fairly useful to
	* debug display issues, especially watermark settings.
	*
	* If an underrun is detected this is logged into dmesg. To avoid flooding logs
	* and occupying the cpu underrun interrupts are disabled after the first
	* occurrence until the next modeset on a given pipe.
	*
	* Note that underrun detection on gmch platforms is a bit more ugly since there
	* is no interrupt (despite that the signalling bit is in the PIPESTAT pipe
	* interrupt register). Also on some other platforms underrun interrupts are
	* shared, which means that if we detect an underrun we need to disable underrun
	* reporting on all pipes.
	*
	* The code also supports underrun detection on the PCH transcoder.
	*/

	static bool ivb_can_enable_err_int(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	struct intel_crtc *crtc;
	enum pipe pipe;

	lockdep_assert_held(&dev_priv->irq_lock);

	for_each_pipe(dev_priv, pipe) {
	crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

	if (crtc->cpu_fifo_underrun_disabled)
	return false;
	}

	return true;
	}

	static bool cpt_can_enable_serr_int(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	enum pipe pipe;
	struct intel_crtc *crtc;

	lockdep_assert_held(&dev_priv->irq_lock);

	for_each_pipe(dev_priv, pipe) {
	crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

	if (crtc->pch_fifo_underrun_disabled)
	return false;
	}

	return true;
	}

	static void i9xx_check_fifo_underruns(struct intel_crtc *crtc)
	{
	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
	i915_reg_t reg = PIPESTAT(crtc->pipe);
	u32 pipestat = I915_READ(reg) & 0xffff0000;

	lockdep_assert_held(&dev_priv->irq_lock);

	if ((pipestat & PIPE_FIFO_UNDERRUN_STATUS) == 0)
	return;

	I915_WRITE(reg, pipestat \| PIPE_FIFO_UNDERRUN_STATUS);
	POSTING_READ(reg);

	trace_intel_cpu_fifo_underrun(dev_priv, crtc->pipe);
	DRM_ERROR("pipe %c underrun\n", pipe_name(crtc->pipe));
	}

	static void i9xx_set_fifo_underrun_reporting(struct drm_device *dev,
	enum pipe pipe,
	bool enable, bool old)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	i915_reg_t reg = PIPESTAT(pipe);
	u32 pipestat = I915_READ(reg) & 0xffff0000;

	lockdep_assert_held(&dev_priv->irq_lock);

	if (enable) {
	I915_WRITE(reg, pipestat \| PIPE_FIFO_UNDERRUN_STATUS);
	POSTING_READ(reg);
	} else {
	if (old && pipestat & PIPE_FIFO_UNDERRUN_STATUS)
	DRM_ERROR("pipe %c underrun\n", pipe_name(pipe));
	}
	}

	static void ironlake_set_fifo_underrun_reporting(struct drm_device *dev,
	enum pipe pipe, bool enable)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	uint32_t bit = (pipe == PIPE_A) ? DE_PIPEA_FIFO_UNDERRUN :
	DE_PIPEB_FIFO_UNDERRUN;

	if (enable)
	ilk_enable_display_irq(dev_priv, bit);
	else
	ilk_disable_display_irq(dev_priv, bit);
	}

	static void ivybridge_check_fifo_underruns(struct intel_crtc *crtc)
	{
	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
	enum pipe pipe = crtc->pipe;
	uint32_t err_int = I915_READ(GEN7_ERR_INT);

	lockdep_assert_held(&dev_priv->irq_lock);

	if ((err_int & ERR_INT_FIFO_UNDERRUN(pipe)) == 0)
	return;

	I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));
	POSTING_READ(GEN7_ERR_INT);

	trace_intel_cpu_fifo_underrun(dev_priv, pipe);
	DRM_ERROR("fifo underrun on pipe %c\n", pipe_name(pipe));
	}

	static void ivybridge_set_fifo_underrun_reporting(struct drm_device *dev,
	enum pipe pipe,
	bool enable, bool old)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	if (enable) {
	I915_WRITE(GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));

	if (!ivb_can_enable_err_int(dev))
	return;

	ilk_enable_display_irq(dev_priv, DE_ERR_INT_IVB);
	} else {
	ilk_disable_display_irq(dev_priv, DE_ERR_INT_IVB);

	if (old &&
	I915_READ(GEN7_ERR_INT) & ERR_INT_FIFO_UNDERRUN(pipe)) {
	DRM_ERROR("uncleared fifo underrun on pipe %c\n",
	pipe_name(pipe));
	}
	}
	}

	static void broadwell_set_fifo_underrun_reporting(struct drm_device *dev,
	enum pipe pipe, bool enable)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);

	if (enable)
	bdw_enable_pipe_irq(dev_priv, pipe, GEN8_PIPE_FIFO_UNDERRUN);
	else
	bdw_disable_pipe_irq(dev_priv, pipe, GEN8_PIPE_FIFO_UNDERRUN);
	}

	static void ibx_set_fifo_underrun_reporting(struct drm_device *dev,
	enum transcoder pch_transcoder,
	bool enable)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	uint32_t bit = (pch_transcoder == TRANSCODER_A) ?
	SDE_TRANSA_FIFO_UNDER : SDE_TRANSB_FIFO_UNDER;

	if (enable)
	ibx_enable_display_interrupt(dev_priv, bit);
	else
	ibx_disable_display_interrupt(dev_priv, bit);
	}

	static void cpt_check_pch_fifo_underruns(struct intel_crtc *crtc)
	{
	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
	enum transcoder pch_transcoder = (enum transcoder) crtc->pipe;
	uint32_t serr_int = I915_READ(SERR_INT);

	lockdep_assert_held(&dev_priv->irq_lock);

	if ((serr_int & SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) == 0)
	return;

	I915_WRITE(SERR_INT, SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));
	POSTING_READ(SERR_INT);

	trace_intel_pch_fifo_underrun(dev_priv, pch_transcoder);
	DRM_ERROR("pch fifo underrun on pch transcoder %s\n",
	transcoder_name(pch_transcoder));
	}

	static void cpt_set_fifo_underrun_reporting(struct drm_device *dev,
	enum transcoder pch_transcoder,
	bool enable, bool old)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);

	if (enable) {
	I915_WRITE(SERR_INT,
	SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));

	if (!cpt_can_enable_serr_int(dev))
	return;

	ibx_enable_display_interrupt(dev_priv, SDE_ERROR_CPT);
	} else {
	ibx_disable_display_interrupt(dev_priv, SDE_ERROR_CPT);

	if (old && I915_READ(SERR_INT) &
	SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder)) {
	DRM_ERROR("uncleared pch fifo underrun on pch transcoder %s\n",
	transcoder_name(pch_transcoder));
	}
	}
	}

	static bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
	enum pipe pipe, bool enable)
	{
	struct drm_i915_private *dev_priv = to_i915(dev);
	struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
	bool old;

	lockdep_assert_held(&dev_priv->irq_lock);

	old = !crtc->cpu_fifo_underrun_disabled;
	crtc->cpu_fifo_underrun_disabled = !enable;

	if (HAS_GMCH_DISPLAY(dev_priv))
	i9xx_set_fifo_underrun_reporting(dev, pipe, enable, old);
	else if (IS_GEN5(dev_priv) \|\| IS_GEN6(dev_priv))
	ironlake_set_fifo_underrun_reporting(dev, pipe, enable);
	else if (IS_GEN7(dev_priv))
	ivybridge_set_fifo_underrun_reporting(dev, pipe, enable, old);
	else if (INTEL_GEN(dev_priv) >= 8)
	broadwell_set_fifo_underrun_reporting(dev, pipe, enable);

	return old;
	}

	/**
	* intel_set_cpu_fifo_underrun_reporting - set cpu fifo underrrun reporting state
	* @dev_priv: i915 device instance
	* @pipe: (CPU) pipe to set state for
	* @enable: whether underruns should be reported or not
	*
	* This function sets the fifo underrun state for @pipe. It is used in the
	* modeset code to avoid false positives since on many platforms underruns are
	* expected when disabling or enabling the pipe.
	*
	* Notice that on some platforms disabling underrun reports for one pipe
	* disables for all due to shared interrupts. Actual reporting is still per-pipe
	* though.
	*
	* Returns the previous state of underrun reporting.
	*/
	bool intel_set_cpu_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
	enum pipe pipe, bool enable)
	{
	unsigned long flags;
	bool ret;

	spin_lock_irqsave(&dev_priv->irq_lock, flags);
	ret = __intel_set_cpu_fifo_underrun_reporting(&dev_priv->drm, pipe,
	enable);
	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);

	return ret;
	}

	/**
	* intel_set_pch_fifo_underrun_reporting - set PCH fifo underrun reporting state
	* @dev_priv: i915 device instance
	* @pch_transcoder: the PCH transcoder (same as pipe on IVB and older)
	* @enable: whether underruns should be reported or not
	*
	* This function makes us disable or enable PCH fifo underruns for a specific
	* PCH transcoder. Notice that on some PCHs (e.g. CPT/PPT), disabling FIFO
	* underrun reporting for one transcoder may also disable all the other PCH
	* error interruts for the other transcoders, due to the fact that there's just
	* one interrupt mask/enable bit for all the transcoders.
	*
	* Returns the previous state of underrun reporting.
	*/
	bool intel_set_pch_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
	enum transcoder pch_transcoder,
	bool enable)
	{
	struct intel_crtc *crtc =
	intel_get_crtc_for_pipe(dev_priv, (enum pipe) pch_transcoder);
	unsigned long flags;
	bool old;

	/*
	* NOTE: Pre-LPT has a fixed cpu pipe -> pch transcoder mapping, but LPT
	* has only one pch transcoder A that all pipes can use. To avoid racy
	* pch transcoder -> pipe lookups from interrupt code simply store the
	* underrun statistics in crtc A. Since we never expose this anywhere
	* nor use it outside of the fifo underrun code here using the "wrong"
	* crtc on LPT won't cause issues.
	*/

	spin_lock_irqsave(&dev_priv->irq_lock, flags);

	old = !crtc->pch_fifo_underrun_disabled;
	crtc->pch_fifo_underrun_disabled = !enable;

	if (HAS_PCH_IBX(dev_priv))
	ibx_set_fifo_underrun_reporting(&dev_priv->drm,
	pch_transcoder,
	enable);
	else
	cpt_set_fifo_underrun_reporting(&dev_priv->drm,
	pch_transcoder,
	enable, old);

	spin_unlock_irqrestore(&dev_priv->irq_lock, flags);
	return old;
	}

	/**
	* intel_cpu_fifo_underrun_irq_handler - handle CPU fifo underrun interrupt
	* @dev_priv: i915 device instance
	* @pipe: (CPU) pipe to set state for
	*
	* This handles a CPU fifo underrun interrupt, generating an underrun warning
	* into dmesg if underrun reporting is enabled and then disables the underrun
	* interrupt to avoid an irq storm.
	*/
	void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
	enum pipe pipe)
	{
	struct intel_crtc *crtc = intel_get_crtc_for_pipe(dev_priv, pipe);

	/* We may be called too early in init, thanks BIOS! */
	if (crtc == NULL)
	return;

	/* GMCH can't disable fifo underruns, filter them. */
	if (HAS_GMCH_DISPLAY(dev_priv) &&
	crtc->cpu_fifo_underrun_disabled)
	return;

	if (intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false)) {
	trace_intel_cpu_fifo_underrun(dev_priv, pipe);
	DRM_ERROR("CPU pipe %c FIFO underrun\n",
	pipe_name(pipe));
	}

	intel_fbc_handle_fifo_underrun_irq(dev_priv);
	}

	/**
	* intel_pch_fifo_underrun_irq_handler - handle PCH fifo underrun interrupt
	* @dev_priv: i915 device instance
	* @pch_transcoder: the PCH transcoder (same as pipe on IVB and older)
	*
	* This handles a PCH fifo underrun interrupt, generating an underrun warning
	* into dmesg if underrun reporting is enabled and then disables the underrun
	* interrupt to avoid an irq storm.
	*/
	void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
	enum transcoder pch_transcoder)
	{
	if (intel_set_pch_fifo_underrun_reporting(dev_priv, pch_transcoder,
	false)) {
	trace_intel_pch_fifo_underrun(dev_priv, pch_transcoder);
	DRM_ERROR("PCH transcoder %s FIFO underrun\n",
	transcoder_name(pch_transcoder));
	}
	}

	/**
	* intel_check_cpu_fifo_underruns - check for CPU fifo underruns immediately
	* @dev_priv: i915 device instance
	*
	* Check for CPU fifo underruns immediately. Useful on IVB/HSW where the shared
	* error interrupt may have been disabled, and so CPU fifo underruns won't
	* necessarily raise an interrupt, and on GMCH platforms where underruns never
	* raise an interrupt.
	*/
	void intel_check_cpu_fifo_underruns(struct drm_i915_private *dev_priv)
	{
	struct intel_crtc *crtc;

	spin_lock_irq(&dev_priv->irq_lock);

	for_each_intel_crtc(&dev_priv->drm, crtc) {
	if (crtc->cpu_fifo_underrun_disabled)
	continue;

	if (HAS_GMCH_DISPLAY(dev_priv))
	i9xx_check_fifo_underruns(crtc);
	else if (IS_GEN7(dev_priv))
	ivybridge_check_fifo_underruns(crtc);
	}

	spin_unlock_irq(&dev_priv->irq_lock);
	}

	/**
	* intel_check_pch_fifo_underruns - check for PCH fifo underruns immediately
	* @dev_priv: i915 device instance
	*
	* Check for PCH fifo underruns immediately. Useful on CPT/PPT where the shared
	* error interrupt may have been disabled, and so PCH fifo underruns won't
	* necessarily raise an interrupt.
	*/
	void intel_check_pch_fifo_underruns(struct drm_i915_private *dev_priv)
	{
	struct intel_crtc *crtc;

	spin_lock_irq(&dev_priv->irq_lock);

	for_each_intel_crtc(&dev_priv->drm, crtc) {
	if (crtc->pch_fifo_underrun_disabled)
	continue;

	if (HAS_PCH_CPT(dev_priv))
	cpt_check_pch_fifo_underruns(crtc);
	}

	spin_unlock_irq(&dev_priv->irq_lock);
	}