[Intel-gfx] [RFC 1/6] drm/i915: Iterate over pipe and skip the disabled one

[Jani Nikula]

On Thu, 23 Jan 2020, Anshuman Gupta <anshuman.gupta at intel.com> wrote:
> It should not be assumed that a disabled display pipe will be
> always last the pipe.
> for_each_pipe() should iterate over I915_MAX_PIPES and check
> for the disabled pipe and skip that pipe so that it should not
> initialize the intel crtc for any disabled pipes.
>
> Few compilation error needed to handle accordingly due to
> change in for_each_pipe() macro.

Really? Please paste.

>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.h | 5 +++--
>  drivers/gpu/drm/i915/i915_irq.c              | 6 ++++--
>  2 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index 028aab728514..47813a50add4 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -312,10 +312,11 @@ enum phy_fia {
>  };
>  
>  #define for_each_pipe(__dev_priv, __p) \
> -	for ((__p) = 0; (__p) < INTEL_NUM_PIPES(__dev_priv); (__p)++)
> +	for ((__p) = 0; (__p) < I915_MAX_PIPES; (__p)++) \

Originally I was envisioning using for_each_set_bit() from bitops.h for
this. It's probably more efficient, however I'm not sure if efficiency
matters much here. The ugly part is that for_each_set_bit() requires an
explicit cast to unsigned long *.

Perhaps this is just as well, it's not wrong, and can always be updated
later.

> +		for_each_if((INTEL_INFO(__dev_priv)->pipe_mask) & BIT(__p))
>  
>  #define for_each_pipe_masked(__dev_priv, __p, __mask) \
> -	for ((__p) = 0; (__p) < INTEL_NUM_PIPES(__dev_priv); (__p)++) \
> +	for_each_pipe(__dev_priv, __p) \
>  		for_each_if((__mask) & BIT(__p))
>  
>  #define for_each_cpu_transcoder_masked(__dev_priv, __t, __mask) \
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 94cb25ac504d..22ecd5bc407e 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1735,11 +1735,12 @@ static void ibx_irq_handler(struct drm_i915_private *dev_priv, u32 pch_iir)
>  	if (pch_iir & SDE_POISON)
>  		DRM_ERROR("PCH poison interrupt\n");
>  
> -	if (pch_iir & SDE_FDI_MASK)
> +	if (pch_iir & SDE_FDI_MASK) {
>  		for_each_pipe(dev_priv, pipe)
>  			DRM_DEBUG_DRIVER("  pipe %c FDI IIR: 0x%08x\n",
>  					 pipe_name(pipe),
>  					 I915_READ(FDI_RX_IIR(pipe)));
> +	}

Are the brace changes really needed? This is what the for_each_if hack
is supposed to tackle.

>  
>  	if (pch_iir & (SDE_TRANSB_CRC_DONE | SDE_TRANSA_CRC_DONE))
>  		DRM_DEBUG_DRIVER("PCH transcoder CRC done interrupt\n");
> @@ -1818,11 +1819,12 @@ static void cpt_irq_handler(struct drm_i915_private *dev_priv, u32 pch_iir)
>  	if (pch_iir & SDE_AUDIO_CP_CHG_CPT)
>  		DRM_DEBUG_DRIVER("Audio CP change interrupt\n");
>  
> -	if (pch_iir & SDE_FDI_MASK_CPT)
> +	if (pch_iir & SDE_FDI_MASK_CPT) {
>  		for_each_pipe(dev_priv, pipe)
>  			DRM_DEBUG_DRIVER("  pipe %c FDI IIR: 0x%08x\n",
>  					 pipe_name(pipe),
>  					 I915_READ(FDI_RX_IIR(pipe)));
> +	}
>  
>  	if (pch_iir & SDE_ERROR_CPT)
>  		cpt_serr_int_handler(dev_priv);

-- 
Jani Nikula, Intel Open Source Graphics Center