[Intel-gfx] [PATCH v2 5/6] drm/i915: Enable FIFO underrun reporting after initial fastset, v2.

[Ville Syrjälä]

On Thu, Nov 09, 2017 at 05:24:57PM +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.
> 
> Changes since v1:
> - Always enable CPU FIFO underrun reporting for >GEN2,
>   and handle GEN2 correctly.

"Correct" is a strong word to use here. I think I should have the
actually correct thing somewhere...

git://github.com/vsyrjala/linux.git gen2_fifo_underrun

Though it seems I haven't managed to write proper commit messages for
it yet.

> 
> Testcase: debugfs_test.read_all_entries
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 3af1e3f74dbb..58bce253f4a8 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12905,6 +12905,7 @@ 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);
> @@ -12912,6 +12913,17 @@ 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 (new_crtc_state->update_pipe &&
> +	    !needs_modeset(&new_crtc_state->base) &&
> +	    old_crtc_state->mode.private_flags & I915_MODE_FLAG_INHERITED) {
> +		if (!IS_GEN2(dev_priv) ||
> +		    new_crtc_state->active_planes & BIT(PLANE_PRIMARY))
> +			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);

I quite dislike having so many platform checks in high level
common code. Maybe we should have some kind of
intel_initial_modeset_done() thing or something?

I don't quite see why that !DDI check is here either.

> +	}
>  }
>  
>  /**
> -- 
> 2.15.0
> 
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-- 
Ville Syrjälä
Intel OTC