Re: [PATCH v5 0/8] drm: rcar-du: Add Color Management Module (CMM)

[Eugeniu Rosca]

Hi Geert,

On Wed, May 27, 2020 at 09:34:30AM +0200, Geert Uytterhoeven wrote:
> On Wed, May 27, 2020 at 9:16 AM Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> wrote:
> > On Tue, Oct 15, 2019 at 12:46:13PM +0200, Jacopo Mondi wrote:
> > > CMM functionalities are retained between suspend/resume cycles (tested with
> > > suspend-to-idle) without requiring a re-programming of the LUT tables.
> >
> > Hmm. Is this backed up by any statement in the HW User's manual?
> > This comes in contrast with the original Renesas CMM implementation [**]
> > which does make use of suspend (where the freeze actually happens).
> >
> > Can we infer, based on your statement, that we could also get rid of
> > the suspend callback in [**]?
> 
> While the CMM state will be retained across suspend-to-idle, I'm quite
> sure it will be lost by suspend-to-RAM, at least on the Salvator-X(S),
> ULCB, and Ebisu development boards, as PSCI will ask the BD9571WMV
> regulator to power down the R-Car SoC.
> 
> So IMHO we do need suspend/resume handling.

That makes sense. I should be more careful about suspend-to-idle
vs suspend-to-ram and not alias the two.

-- 
Best regards,
Eugeniu Rosca