Re: [PATCH v4 3/4] drm/i915: Use new CRC debugfs API

[Tomeu Vizoso]

On 2 September 2016 at 17:18, Emil Velikov <emil.l.velikov@xxxxxxxxx> wrote:
> Hi Tomeu,
>
> IMHO it would be better to split out the refactoring into preparatory
> patch. It brings a minor change which (not 100% sure on that) should
> not cause issues but is worth pointing out.

I think at this point it would make sense to change the series
structure only if there was a strong reason, as a few people have
already looked at the patches already.

> On 5 August 2016 at 11:45, Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> wrote:
>
>> +static int do_set_crc_source(struct drm_device *dev, enum pipe pipe,
>> +                            enum intel_pipe_crc_source source)
>> +{
>
>> +       if (source == INTEL_PIPE_CRC_SOURCE_NONE) {
> Nit: use !source here or sourse != INTEL_PIPE_CRC_SOURCE_NONE
> elsewhere in the code ?

Agreed.

>
>> @@ -693,10 +718,11 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe,
>>                 spin_unlock_irq(&pipe_crc->lock);
>>         }
>>
>> -       pipe_crc->source = source;
>> +       ret = do_set_crc_source(dev, pipe, source);
>> +       if (ret)
>> +               goto out;
>>
> We seem to have modified pipe_crc even if the new function fails.
> Haven't check if it matters, but definatelly not ideal.

If we had modified pipe_crc that's because we were trying to start CRC
capture and we initialized the entry storage. As CRC generation is
disabled, those changes have no effects. When CRC capture is attempted
again, they will be initialized again.

To avoid this we would need to split the HW programming in two
functions and I'm not sure it would be worth it.

>> @@ -720,15 +746,6 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe,
>>                 spin_unlock_irq(&pipe_crc->lock);
>>
>>                 kfree(entries);
>> -
>> -               if (IS_G4X(dev))
>> -                       g4x_undo_pipe_scramble_reset(dev, pipe);
>> -               else if (IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev))
>> -                       vlv_undo_pipe_scramble_reset(dev, pipe);
>> -               else if (IS_HASWELL(dev) && pipe == PIPE_A)
>> -                       hsw_trans_edp_pipe_A_crc_wa(dev, false);
>> -
>> -               hsw_enable_ips(crtc);
> The above is the piece I have in mind:
> With the introduction of do_set_crc_source() the above are executed
> prior to the intel_wait_for_vblank() call.
>
> Afaics this will not cause any functional change, then again I'm not
> that familiar with the i915 vblank code.

Yeah, not sure either of when do those changes take effect.

>> +int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name,
>> +                             size_t *values_cnt)
>> +{
>
>> +       ret = do_set_crc_source(crtc->dev, crtc->index, source);
>> +
>> +       intel_display_power_put(dev_priv, power_domain);
>> +
>> +       *values_cnt = 5;
>> +
> Please don't overwrite values_cnt if the function fails.

Done.

Thanks,

Tomeu

> Regards,
> Emil
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