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

[Maarten Lankhorst]

Op 09-11-17 om 18:15 schreef 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?

We have nothing better atm, I'm ok with completely ignoring FIFO underruns
when inheriting on GEN2 as well, would that work for you for now?

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

Oh that one can be nuked I think, was under the mistaken impression it could be set
with DDI, but didn't see anywhere in the code the pch fifo underruns were set for DDI.

The has_pch_encoder check should be enough on its own after more careful inspection. :-)

>> +	}
>>  }
>>  
>>  /**
>> -- 
>> 2.15.0
>>
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