[PATCH v3 3/3] drm/omapdrm: Implement gamma_lut atomic crtc property

[Daniel Vetter]

On Tue, May 24, 2016 at 03:15:46PM +0300, Tomi Valkeinen wrote:
> Hi,
> 
> On 24/05/16 12:16, Jyri Sarha wrote:
> > Implement gamma_lut atomic crtc property, set crtc gamma size to 256
> > for all crtcs and use drm_atomic_helper_legacy_gamma_set() as
> > gamma_set func. The tv-out crtc has 1024 element gamma table (with
> > 10bit precision) in HW, but current Xorg server does not accept
> > anything else but 256 elements so that is used for all CRTCs. The dss
> > dispc API converts table of any length for HW and uses linear
> > interpolation in the process.
> > 
> > Signed-off-by: Jyri Sarha <jsarha at ti.com>
> > ---
> >  drivers/gpu/drm/omapdrm/omap_crtc.c | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
> > index 075f2bb..d5210fe 100644
> > --- a/drivers/gpu/drm/omapdrm/omap_crtc.c
> > +++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
> > @@ -384,6 +384,15 @@ static void omap_crtc_atomic_flush(struct drm_crtc *crtc,
> >  
> >  	WARN_ON(omap_crtc->vblank_irq.registered);
> >  
> > +	if (crtc->state->color_mgmt_changed) {
> > +		struct drm_color_lut *lut = (struct drm_color_lut *)
> > +			crtc->state->gamma_lut->data;
> > +		unsigned int length = crtc->state->gamma_lut->length /
> > +			sizeof(*lut);
> > +
> > +		dispc_mgr_set_gamma(omap_crtc->channel, lut, length);
> > +	}
> > +
> >  	if (dispc_mgr_is_enabled(omap_crtc->channel)) {
> >  
> >  		DBG("%s: GO", omap_crtc->name);
> > @@ -460,6 +469,7 @@ static const struct drm_crtc_funcs omap_crtc_funcs = {
> >  	.set_config = drm_atomic_helper_set_config,
> >  	.destroy = omap_crtc_destroy,
> >  	.page_flip = drm_atomic_helper_page_flip,
> > +	.gamma_set = drm_atomic_helper_legacy_gamma_set,
> >  	.set_property = drm_atomic_helper_crtc_set_property,
> >  	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
> >  	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
> > @@ -534,6 +544,16 @@ struct drm_crtc *omap_crtc_init(struct drm_device *dev,
> >  
> >  	drm_crtc_helper_add(crtc, &omap_crtc_helper_funcs);
> >  
> > +	/* The dispc API adapts to what ever size, but the HW supports
> > +	 * 256 element gamma table for LCDs and 1024 element table for
> > +	 * OMAP_DSS_CHANNEL_DIGIT. X server assumes 256 element gamma
> > +	 * tables so lets use that. Size of HW gamma table can be
> > +	 * extracted with dispc_mgr_gamma_size(). If it returns 0
> > +	 * gamma table is not supprted.
> > +	 */
> > +	if (dispc_mgr_gamma_size(channel))
> > +		drm_mode_crtc_set_gamma_size(crtc, 256);
> > +
> >  	omap_plane_install_properties(crtc->primary, &crtc->base);
> >  
> >  	omap_crtcs[channel] = omap_crtc;
> > 
> 
> I think you also need to attach the GAMMA_LUT and GAMMA_LUT_SIZE
> properties to the crtc. Otherwise only the legacy API is available. See
> drm_helper_crtc_enable_color_mgmt() (we can't use that, but as an example).

Hm, the idea once was that this helper doesn't register the props if you
pass in a size of 0. And if we add a bool has_ctm on top, you could reuse
that helper.

The other offending bit is that it's imo not a helper, but really should
be a core part next to setting up the gamma props in drm_crtc.c imo. So in
the end:

void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
				int degamma_lut_size,
				bool has_ctm,
				int gamma_lut_size);

Volunteered to apply that bit of interface polish?

Thanks, Daniel

> 
>  Tomi
> 




-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch