On 05/09/2019 13:05, Laurent Pinchart wrote:
Hi Jyri,
On Thu, Sep 05, 2019 at 01:00:51PM +0300, Jyri Sarha wrote:
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.
We call omap_crtc_write_crtc_properties() in omap_crtc_atomic_flush(), so that's at every page flip...
Still, the mgr_setup() accesses five different registers even if we do not touch CPR settings (another 4 registers). All of those have static values in the mainline omapdrm (there are custom properties to control those in ti-linux).
I would rather keep this patch as it is and implement another one with a cached struct omap_overlay_manager_info, that calls mgr_setup() only if the info values have changed.
With the cached values in place the unneeded conversion arithmetic can also be skipped based on color_mgmt_changed.
BR, Jyri