On 05/09/2019 00:52, Laurent Pinchart wrote:
>>>>>> static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
>>>>>> {
>>>>>> struct omap_drm_private *priv = crtc->dev->dev_private;
>>>>>> @@ -402,7 +428,16 @@ static void omap_crtc_write_crtc_properties(struct drm_crtc *crtc)
>>>>>> info.default_color = 0x000000;
>>>>>> info.trans_enabled = false;
>>>>>> info.partial_alpha_enabled = false;
>>>>>> - info.cpr_enable = false;
>>>>>> +
>>>>>> + if (crtc->state->ctm) {
>>>>>> + struct drm_color_ctm *ctm =
>>>>>> + (struct drm_color_ctm *) crtc->state->ctm->data;
>>>>>> +
>>>>>> + info.cpr_enable = true;
>>>>>> + omap_crtc_cpr_coefs_from_ctm(ctm, &info.cpr_coefs);
>>>>> As an optimisation it would be nice to only write the coefficients when
>>>>> they actually change. That could be implemented on top of this series.
>>>> E.g. apply this ?
>>>>
>>>> - if (crtc->state->ctm)
>>>> + if (crtc->state->color_mgmt_changed && crtc->state->ctm)
>>> Something like that, but .mgr_setup() should then be taught not to write
>>> unchanged CTM tables to registers. Do you think it would be worth it ?
>> Hmmm, jess I should do it like this:
>> if (crtc->state->color_mgmt_changed) {
>> if (crtc->state->ctm) {
>> ...
>>>>>> + } else {
>>>>>> + info.cpr_enable = false;
>>>>>> + }
>> }
>>
>> This way the whole CPR functionality is turned off, if the there is no
>> CTM in the crtc state.
> Yes, but you would also need to update .mgr_setup() :-) A new
> color_mgmt_changed flag would be needed in the info structure too.
>
I am starting to thing that such an "optimization" may not be worth the
added complexity. The arithmetic and writing three registers is not that
costly and we do not commit a new crtc state that often.
If we later consider otherwise we can add the optimization as a separate
patch.
BR,
Jyri
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