Re: [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.sh...@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