[Intel-gfx] [PATCH] drm/i915/display: Add a debugfs entry for fifo underruns

[Swati Sharma]

Thanks Andi and Jani N for the review comments.
Sorry for the delay.
Will send the next rev soon.

On 14-Feb-23 5:55 PM, Jani Nikula wrote:
> On Wed, 08 Feb 2023, Andi Shyti <andi.shyti at linux.intel.com> wrote:
>> Hi Swati,
>>
>> [...]
>>
>>> +static void intel_fifo_underrun_inc_count(struct intel_crtc *crtc,
>>> +					  bool is_cpu_fifo)
>>
>> I'm not a big fan of the true/false parameters in functions. I
>> actually hate them because it's never clear from the caller what
>> the true/false means.
>>
>> Isn't it clear to just have some wrappers
>>
>> #define intel_fifo_underrun_inc_cpu_count(...)
>> #define intel_fifo_underrun_inc_cph_count(...)
>>
>> or similar?
>>
>>> +{
>>> +#ifdef CONFIG_DEBUG_FS
>>> +	if (is_cpu_fifo)
>>> +		crtc->cpu_fifo_underrun_count++;
>>> +	else
>>> +		crtc->pch_fifo_underrun_count++;
>>> +#endif
>>> +}
>>> +
>>>   static void i9xx_check_fifo_underruns(struct intel_crtc *crtc)
>>>   {
>>>   	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
>>> @@ -103,6 +114,7 @@ static void i9xx_check_fifo_underruns(struct intel_crtc *crtc)
>>>   	intel_de_write(dev_priv, reg, enable_mask | PIPE_FIFO_UNDERRUN_STATUS);
>>>   	intel_de_posting_read(dev_priv, reg);
>>>   
>>> +	intel_fifo_underrun_inc_count(crtc, true);
>>>   	trace_intel_cpu_fifo_underrun(dev_priv, crtc->pipe);
>>>   	drm_err(&dev_priv->drm, "pipe %c underrun\n", pipe_name(crtc->pipe));
>>>   }
>>> @@ -156,6 +168,7 @@ static void ivb_check_fifo_underruns(struct intel_crtc *crtc)
>>>   	intel_de_write(dev_priv, GEN7_ERR_INT, ERR_INT_FIFO_UNDERRUN(pipe));
>>>   	intel_de_posting_read(dev_priv, GEN7_ERR_INT);
>>>   
>>> +	intel_fifo_underrun_inc_count(crtc, true);
>>>   	trace_intel_cpu_fifo_underrun(dev_priv, pipe);
>>>   	drm_err(&dev_priv->drm, "fifo underrun on pipe %c\n", pipe_name(pipe));
>>>   }
>>> @@ -244,6 +257,7 @@ static void cpt_check_pch_fifo_underruns(struct intel_crtc *crtc)
>>>   		       SERR_INT_TRANS_FIFO_UNDERRUN(pch_transcoder));
>>>   	intel_de_posting_read(dev_priv, SERR_INT);
>>>   
>>> +	intel_fifo_underrun_inc_count(crtc, false);
>>>   	trace_intel_pch_fifo_underrun(dev_priv, pch_transcoder);
>>>   	drm_err(&dev_priv->drm, "pch fifo underrun on pch transcoder %c\n",
>>>   		pipe_name(pch_transcoder));
>>> @@ -286,6 +300,11 @@ static bool __intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
>>>   
>>>   	old = !crtc->cpu_fifo_underrun_disabled;
>>>   	crtc->cpu_fifo_underrun_disabled = !enable;
>>> +#ifdef CONFIG_DEBUG_FS
>>> +	/* don't reset count in fifo underrun irq path */
>>> +	if (!in_irq() && !enable)
>>> +		crtc->cpu_fifo_underrun_count = 0;
>>> +#endif
>>>   
>>>   	if (HAS_GMCH(dev_priv))
>>>   		i9xx_set_fifo_underrun_reporting(dev, pipe, enable, old);
>>> @@ -365,6 +384,11 @@ bool intel_set_pch_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
>>>   
>>>   	old = !crtc->pch_fifo_underrun_disabled;
>>>   	crtc->pch_fifo_underrun_disabled = !enable;
>>> +#ifdef CONFIG_DEBUG_FS
>>> +	/* don't reset count in fifo underrun irq path */
>>> +	if (!in_irq() && !enable)
>>> +		crtc->pch_fifo_underrun_count = 0;
>>> +#endif
>>
>> All these ifdefs are a bit ugly. Can we put all these stuff
>> inside the debugfs.c file that is compiled only if DEBUG_FS is
>> configured?
> 
> The opposite, the debugfs should be added in this file instead. :)
> 
> See my reply.
> 
> BR,
> Jani.
> 
> 
> 
> 
>>
>> Andi
>>
>>>   
>>>   	if (HAS_PCH_IBX(dev_priv))
>>>   		ibx_set_fifo_underrun_reporting(&dev_priv->drm,
>>> @@ -434,6 +458,7 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
>>>   			drm_err(&dev_priv->drm, "CPU pipe %c FIFO underrun\n", pipe_name(pipe));
>>>   	}
>>>   
>>> +	intel_fifo_underrun_inc_count(crtc, true);
>>>   	intel_fbc_handle_fifo_underrun_irq(dev_priv);
>>>   }
> 

-- 
~Swati Sharma