[Intel-gfx] [PATCH 2/3] drm/i915: Enable FIFO underrun reporting after initial fastset

[Daniel Vetter]

On Wed, Nov 08, 2017 at 10:29:21AM +0100, Maarten Lankhorst wrote:
> The firmware may have set up the pipe correctly, but the FIFO
> underrun and CRC interrupts are likely not enabled.
> 
> This resulted in debugfs_test.read_all_entries failing on haswell,
> because of a timeout when reading the crc debugfs entry.
> 
> Solve this by enabling FIFO underrun reporting after the initial
> fastset, which lets interrupts be generated as expected.
> 
> Testcase: debugfs_test.read_all_entries
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 737de251d0f8..8d42e6a910d4 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12875,6 +12875,7 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
>  static void intel_finish_crtc_commit(struct drm_crtc *crtc,
>  				     struct drm_crtc_state *old_crtc_state)
>  {
> +	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
>  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>  	struct intel_atomic_state *old_intel_state =
>  		to_intel_atomic_state(old_crtc_state->state);
> @@ -12882,6 +12883,15 @@ static void intel_finish_crtc_commit(struct drm_crtc *crtc,
>  		intel_atomic_get_new_crtc_state(old_intel_state, intel_crtc);
>  
>  	intel_pipe_update_end(new_crtc_state);
> +
> +	if (HAS_PCH_SPLIT(dev_priv) && new_crtc_state->update_pipe &&

The HAS_PCH_SPLIT looks very wrong. Just enable fifo underrun reporting
already for the relevant pipes. I think really the only check you need
here is for I915_MODE_FLAG_INHERITED and then the has_pch_encoder check
too. Everything else looks like cargo culting conditions.

Note that at driver boot-up _all_ fifo underrun reporting is disabled by
default, so we really need to enable it everywhere explicitly.

Placement looks good since it's after the wm update. That's really the
only reason we don't enable it straight at driver load, since we don't
entirely trust the firmware wm settings.
-Daniel

> +	    !needs_modeset(&new_crtc_state->base) &&
> +	    old_crtc_state->mode.private_flags & I915_MODE_FLAG_INHERITED) {
> +		intel_set_cpu_fifo_underrun_reporting(dev_priv, intel_crtc->pipe, true);
> +
> +		if (new_crtc_state->has_pch_encoder && !HAS_DDI(dev_priv))
> +			intel_set_pch_fifo_underrun_reporting(dev_priv, intel_crtc->pipe, true);
> +	}
>  }
>  
>  /**
> -- 
> 2.15.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch