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SubjectRe: [PATCH v3 14/14] drm: rcar-du: Force CMM enablement when resuming
Hi Jacopo,

On Thu, Sep 05, 2019 at 12:58:09PM +0200, Jacopo Mondi wrote:
> On Tue, Aug 27, 2019 at 03:05:17AM +0300, Laurent Pinchart wrote:
> > Hi Jacopo,
> >
> > (Question for Daniel below)
> >
> > Thank you for the patch.
> >
> > On Sun, Aug 25, 2019 at 03:51:54PM +0200, Jacopo Mondi wrote:
> >> When resuming from system suspend, the DU driver is responsible for
> >> reprogramming and enabling the CMM unit if it was in use at the time
> >> the system entered the suspend state.
> >>
> >> Force the color_mgmt_changed flag to true if any of the DRM color
> >> transformation properties was set in the CRTC state duplicated at
> >> suspend time, as the CMM gets reprogrammed only if said flag is active in
> >> the rcar_du_atomic_commit_update_cmm() method.
> >>
> >> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> >> ---
> >> drivers/gpu/drm/rcar-du/rcar_du_drv.c | 21 +++++++++++++++++++++
> >> 1 file changed, 21 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> >> index 018480a8f35c..6e38495fb78f 100644
> >> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> >> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> >> @@ -17,6 +17,7 @@
> >> #include <linux/slab.h>
> >> #include <linux/wait.h>
> >>
> >> +#include <drm/drm_atomic.h>
> >> #include <drm/drm_atomic_helper.h>
> >> #include <drm/drm_fb_cma_helper.h>
> >> #include <drm/drm_fb_helper.h>
> >> @@ -482,6 +483,26 @@ static int rcar_du_pm_suspend(struct device *dev)
> >> static int rcar_du_pm_resume(struct device *dev)
> >> {
> >> struct rcar_du_device *rcdu = dev_get_drvdata(dev);
> >> + struct drm_atomic_state *state = rcdu->ddev->mode_config.suspend_state;
> >> + unsigned int i;
> >> +
> >> + for (i = 0; i < rcdu->num_crtcs; ++i) {
> >> + struct drm_crtc *crtc = &rcdu->crtcs[i].crtc;
> >> + struct drm_crtc_state *crtc_state;
> >> +
> >> + crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);
> >> + if (!crtc_state)
> >> + continue;
> >
> > Shouldn't you get the new state here ?
>
> I have followed the drm_atomic_helper_suspend() call stack, that calls
> drm_atomic_helper_duplicate_state() which then assign the crtct state
> with drm_atomic_get_crtc_state(), where I read:
>
> crtc_state = drm_atomic_get_existing_crtc_state(state, crtc);
> ...
> state->crtcs[index].state = crtc_state;
> state->crtcs[index].old_state = crtc->state;
> state->crtcs[index].new_state = crtc_state;
>
> So state or new_state for the purpose of getting back the crtc state
> are the same if I'm not mistaken.

It seems to be the case, but the documentation of
drm_atomic_get_existing_crtc_state() states

* This function is deprecated, @drm_atomic_get_old_crtc_state or
* @drm_atomic_get_new_crtc_state should be used instead.

I would thus use drm_atomic_get_new_crtc_state().

> >> +
> >> + /*
> >> + * Force re-enablement of CMM after system resume if any
> >> + * of the DRM color transformation properties was set in
> >> + * the state saved at system suspend time.
> >> + */
> >> + if (crtc_state->gamma_lut || crtc_state->degamma_lut ||
> >> + crtc_state->ctm)
> >
> > We don't support degamma_lut or crm, so I would drop those.
>
> yeah, I added them as it was less code to change when we'll support
> them. But for now they could be removed.
>
> > With these small issues addressed,
> >
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >
> > Shouldn't we however squash this with the previous patch to avoid
> > bisection issues ?
>
> Which one in your opinion?
> "drm: rcar-du: kms: Update CMM in atomic commit tail" ?
> It seems to me they do quite different things though..

Yes, but suspend/resume will be broken after 13/14 without 14/14. Not
the end of the world, but not really nice if we need to bisect
suspend/resume issues.

> >> + crtc_state->color_mgmt_changed = true;
> >
> > Daniel, is this something that would make sense in the KMS core (or
> > helpers) ?
> >
> >> + }
> >>
> >> return drm_mode_config_helper_resume(rcdu->ddev);
> >> }

--
Regards,

Laurent Pinchart

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