Re: [PATCH v3] drm/i915: Remove unused underrun irq/reporting bits

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Oct 15, 2024 at 01:35:03PM +0530, Sai Teja Pottumuttu wrote:
> Underrun recovery was defeatured and was never brought into usage.
> Thus we can remove the underrun recovery interrupt/reporting
> register bits and related logic introduced to detect/report soft,
> hard, port underruns.
> 
> Essentially this is a revert of the commit 8bcc0840cf7c
> ("drm/i915/xelpd: Enhanced pipe underrun reporting") which originally
> added this functionality. Also note that PIPE_STATUS_UNDERRUN bit in
> PIPESTATUS still stays relevant but we would move back to not
> clearing this sticky bit as we are not using any information from
> this register.
> 
> v2: Extend commit message to add more details (Matt Roper)
> v3: Fix the old commit mention in commit message
> 
> Signed-off-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
> Reviewed-by: Matt Roper <matthew.d.roper@intel.com>

pushed, thanks for the patch and review

> ---
>  .../gpu/drm/i915/display/intel_display_irq.c  | 19 +-----
>  .../gpu/drm/i915/display/intel_display_irq.h  |  1 -
>  .../drm/i915/display/intel_fifo_underrun.c    | 58 ++-----------------
>  drivers/gpu/drm/i915/i915_reg.h               |  9 ---
>  4 files changed, 8 insertions(+), 79 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_irq.c b/drivers/gpu/drm/i915/display/intel_display_irq.c
> index a4367ddc7a44..827891070461 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_irq.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_irq.c
> @@ -1021,17 +1021,6 @@ static u32 gen8_de_pipe_flip_done_mask(struct drm_i915_private *i915)
>  		return GEN8_PIPE_PRIMARY_FLIP_DONE;
>  }
>  
> -u32 gen8_de_pipe_underrun_mask(struct drm_i915_private *dev_priv)
> -{
> -	u32 mask = GEN8_PIPE_FIFO_UNDERRUN;
> -
> -	if (DISPLAY_VER(dev_priv) >= 13)
> -		mask |= XELPD_PIPE_SOFT_UNDERRUN |
> -			XELPD_PIPE_HARD_UNDERRUN;
> -
> -	return mask;
> -}
> -
>  static void gen8_read_and_ack_pch_irqs(struct drm_i915_private *i915, u32 *pch_iir, u32 *pica_iir)
>  {
>  	u32 pica_ier = 0;
> @@ -1177,7 +1166,7 @@ void gen8_de_irq_handler(struct drm_i915_private *dev_priv, u32 master_ctl)
>  		if (iir & GEN8_PIPE_CDCLK_CRC_DONE)
>  			hsw_pipe_crc_irq_handler(dev_priv, pipe);
>  
> -		if (iir & gen8_de_pipe_underrun_mask(dev_priv))
> +		if (iir & GEN8_PIPE_FIFO_UNDERRUN)
>  			intel_cpu_fifo_underrun_irq_handler(dev_priv, pipe);
>  
>  		fault_errors = iir & gen8_de_pipe_fault_mask(dev_priv);
> @@ -1617,8 +1606,7 @@ void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
>  				     u8 pipe_mask)
>  {
>  	struct intel_uncore *uncore = &dev_priv->uncore;
> -	u32 extra_ier = GEN8_PIPE_VBLANK |
> -		gen8_de_pipe_underrun_mask(dev_priv) |
> +	u32 extra_ier = GEN8_PIPE_VBLANK | GEN8_PIPE_FIFO_UNDERRUN |
>  		gen8_de_pipe_flip_done_mask(dev_priv);
>  	enum pipe pipe;
>  
> @@ -1807,8 +1795,7 @@ void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
>  			GEN12_DSB_INT(INTEL_DSB_2);
>  
>  	de_pipe_enables = de_pipe_masked |
> -		GEN8_PIPE_VBLANK |
> -		gen8_de_pipe_underrun_mask(dev_priv) |
> +		GEN8_PIPE_VBLANK | GEN8_PIPE_FIFO_UNDERRUN |
>  		gen8_de_pipe_flip_done_mask(dev_priv);
>  
>  	de_port_enables = de_port_masked;
> diff --git a/drivers/gpu/drm/i915/display/intel_display_irq.h b/drivers/gpu/drm/i915/display/intel_display_irq.h
> index 4b493cff7b8e..b077712b7be1 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_irq.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_irq.h
> @@ -33,7 +33,6 @@ void ibx_disable_display_interrupt(struct drm_i915_private *i915, u32 bits);
>  
>  void gen8_irq_power_well_post_enable(struct drm_i915_private *i915, u8 pipe_mask);
>  void gen8_irq_power_well_pre_disable(struct drm_i915_private *i915, u8 pipe_mask);
> -u32 gen8_de_pipe_underrun_mask(struct drm_i915_private *i915);
>  
>  int i8xx_enable_vblank(struct drm_crtc *crtc);
>  int i915gm_enable_vblank(struct drm_crtc *crtc);
> diff --git a/drivers/gpu/drm/i915/display/intel_fifo_underrun.c b/drivers/gpu/drm/i915/display/intel_fifo_underrun.c
> index 745ce22afb89..cda1daf4cdea 100644
> --- a/drivers/gpu/drm/i915/display/intel_fifo_underrun.c
> +++ b/drivers/gpu/drm/i915/display/intel_fifo_underrun.c
> @@ -192,35 +192,15 @@ static void ivb_set_fifo_underrun_reporting(struct drm_device *dev,
>  	}
>  }
>  
> -static u32
> -icl_pipe_status_underrun_mask(struct drm_i915_private *dev_priv)
> -{
> -	u32 mask = PIPE_STATUS_UNDERRUN;
> -
> -	if (DISPLAY_VER(dev_priv) >= 13)
> -		mask |= PIPE_STATUS_SOFT_UNDERRUN_XELPD |
> -			PIPE_STATUS_HARD_UNDERRUN_XELPD |
> -			PIPE_STATUS_PORT_UNDERRUN_XELPD;
> -
> -	return mask;
> -}
> -
>  static void bdw_set_fifo_underrun_reporting(struct drm_device *dev,
>  					    enum pipe pipe, bool enable)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(dev);
> -	u32 mask = gen8_de_pipe_underrun_mask(dev_priv);
> -
> -	if (enable) {
> -		if (DISPLAY_VER(dev_priv) >= 11)
> -			intel_de_write(dev_priv,
> -				       ICL_PIPESTATUS(dev_priv, pipe),
> -				       icl_pipe_status_underrun_mask(dev_priv));
>  
> -		bdw_enable_pipe_irq(dev_priv, pipe, mask);
> -	} else {
> -		bdw_disable_pipe_irq(dev_priv, pipe, mask);
> -	}
> +	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,
> @@ -404,7 +384,6 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>  {
>  	struct intel_display *display = &dev_priv->display;
>  	struct intel_crtc *crtc = intel_crtc_for_pipe(display, pipe);
> -	u32 underruns = 0;
>  
>  	/* We may be called too early in init, thanks BIOS! */
>  	if (crtc == NULL)
> @@ -415,37 +394,10 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>  	    crtc->cpu_fifo_underrun_disabled)
>  		return;
>  
> -	/*
> -	 * Starting with display version 11, the PIPE_STAT register records
> -	 * whether an underrun has happened, and on XELPD+, it will also record
> -	 * whether the underrun was soft/hard and whether it was triggered by
> -	 * the downstream port logic.  We should clear these bits (which use
> -	 * write-1-to-clear logic) too.
> -	 *
> -	 * Note that although the IIR gives us the same underrun and soft/hard
> -	 * information, PIPE_STAT is the only place we can find out whether
> -	 * the underrun was caused by the downstream port.
> -	 */
> -	if (DISPLAY_VER(dev_priv) >= 11) {
> -		underruns = intel_de_read(dev_priv,
> -					  ICL_PIPESTATUS(dev_priv, pipe)) &
> -			icl_pipe_status_underrun_mask(dev_priv);
> -		intel_de_write(dev_priv, ICL_PIPESTATUS(dev_priv, pipe),
> -			       underruns);
> -	}
> -
>  	if (intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false)) {
>  		trace_intel_cpu_fifo_underrun(display, pipe);
>  
> -		if (DISPLAY_VER(dev_priv) >= 11)
> -			drm_err(&dev_priv->drm, "CPU pipe %c FIFO underrun: %s%s%s%s\n",
> -				pipe_name(pipe),
> -				underruns & PIPE_STATUS_SOFT_UNDERRUN_XELPD ? "soft," : "",
> -				underruns & PIPE_STATUS_HARD_UNDERRUN_XELPD ? "hard," : "",
> -				underruns & PIPE_STATUS_PORT_UNDERRUN_XELPD ? "port," : "",
> -				underruns & PIPE_STATUS_UNDERRUN ? "transcoder," : "");
> -		else
> -			drm_err(&dev_priv->drm, "CPU pipe %c FIFO underrun\n", pipe_name(pipe));
> +		drm_err(&dev_priv->drm, "CPU pipe %c FIFO underrun\n", pipe_name(pipe));
>  	}
>  
>  	intel_fbc_handle_fifo_underrun_irq(&dev_priv->display);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 818142f5a10c..405f409e9761 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1735,13 +1735,6 @@
>  #define   PIPE_MISC2_FLIP_INFO_PLANE_SEL_MASK		REG_GENMASK(2, 0) /* tgl+ */
>  #define   PIPE_MISC2_FLIP_INFO_PLANE_SEL(plane_id)	REG_FIELD_PREP(PIPE_MISC2_FLIP_INFO_PLANE_SEL_MASK, (plane_id))
>  
> -#define _ICL_PIPE_A_STATUS			0x70058
> -#define ICL_PIPESTATUS(dev_priv, pipe)			_MMIO_PIPE2(dev_priv, pipe, _ICL_PIPE_A_STATUS)
> -#define   PIPE_STATUS_UNDERRUN				REG_BIT(31)
> -#define   PIPE_STATUS_SOFT_UNDERRUN_XELPD		REG_BIT(28)
> -#define   PIPE_STATUS_HARD_UNDERRUN_XELPD		REG_BIT(27)
> -#define   PIPE_STATUS_PORT_UNDERRUN_XELPD		REG_BIT(26)
> -
>  #define VLV_DPFLIPSTAT				_MMIO(VLV_DISPLAY_BASE + 0x70028)
>  #define   PIPEB_LINE_COMPARE_INT_EN			REG_BIT(29)
>  #define   PIPEB_HLINE_INT_EN			REG_BIT(28)
> @@ -2512,9 +2505,7 @@
>  #define  GEN12_PIPEDMC_INTERRUPT	REG_BIT(26) /* tgl+ */
>  #define  GEN12_PIPEDMC_FAULT		REG_BIT(25) /* tgl+ */
>  #define  MTL_PIPEDMC_ATS_FAULT		REG_BIT(24) /* mtl+ */
> -#define  XELPD_PIPE_SOFT_UNDERRUN	REG_BIT(22) /* adl/dg2+ */
>  #define  GEN11_PIPE_PLANE7_FAULT	REG_BIT(22) /* icl/tgl */
> -#define  XELPD_PIPE_HARD_UNDERRUN	REG_BIT(21) /* adl/dg2+ */
>  #define  GEN11_PIPE_PLANE6_FAULT	REG_BIT(21) /* icl/tgl */
>  #define  GEN11_PIPE_PLANE5_FAULT	REG_BIT(20) /* icl+ */
>  #define  GEN12_PIPE_VBLANK_UNMOD	REG_BIT(19) /* tgl+ */
> -- 
> 2.34.1
>