[PATCH v5] drm/fsl-dcu: Implement gamma_lut atomic crtc properties

[Meng Yi]

Hi Stefan,

> 
> How did you actually test that? I have a hard time to get anything useable with
> this code.
> 
> The display looks completely borked (colors are way off, and at random either
> too dark or too bright).
> 
> I then also added Gamma 1.0 (and different values) to the Monitor section of
> xorg.conf, but still not really usable.
> 

I just did few more test using libdrm which had been modified for testing gamma. 
And I find you are right. It's my negligence that just tested one case for gamma using all 0xff;


.....

> >  			drm_crtc_send_vblank_event(crtc, event);
> >  		spin_unlock_irq(&crtc->dev->event_lock);
> >  	}
> > +
> > +	if (crtc->state->color_mgmt_changed && crtc->state->gamma_lut)
> > +		fsl_crtc_gamma_set(crtc, (struct drm_color_lut *)
> > +				   crtc->state->gamma_lut->data, 256);
> 
> So this is called while the CRTC is enabled. Others do it there too, but I think in
> our case we should not. The reference manual says:
> 
> "The gamma table can only be read or written when the 2D-ACE is not enabled
> or during the vertical blanking period."
> 

Yes, now gamma correction function behavior weird.
When setting gamma table within crtc enable during initializing, it works correctly. And not right during runtime so far.


Thanks,
Meng