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

[Gotthard Voellmeke]

Added Hien-san, Michael K. from Renesas.

-----Original Message-----
From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Sent: Mittwoch, 27. Mai 2020 09:35
To: REE erosca@xxxxxxxxxxxxxx <erosca@xxxxxxxxxxxxxx>
Cc: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>; Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>; Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>; Simon Horman <horms@xxxxxxxxxxxx>; Ulrich Hecht <uli+renesas@xxxxxxxx>; VenkataRajesh.Kalakodima@xxxxxxxxxxxx; David Airlie <airlied@xxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; KOJI MATSUOKA <koji.matsuoka.xm@xxxxxxxxxxx>; muroya@xxxxxxxxx; Harsha.ManjulaMallikarjun@xxxxxxxxxxxx; Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>; Sean Paul <seanpaul@xxxxxxxxxxxx>; Linux-Renesas <linux-renesas-soc@xxxxxxxxxxxxxxx>; DRI Development <dri-devel@xxxxxxxxxxxxxxxxxxxxx>; Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; Michael Dege <michael.dege@xxxxxxxxxxx>; Gotthard Voellmeke <gotthard.voellmeke@xxxxxxxxxxx>; REE efriedrich@xxxxxxxxxxxxxx <efriedrich@xxxxxxxxxxxxxx>; Michael Rodin <mrodin@xxxxxxxxxxxxxx>; ChaitanyaKumar.Borah@xxxxxxxxxxxx; Eugeniu Rosca <roscaeugeniu@xxxxxxxxx>
Subject: Re: [PATCH v5 0/8] drm: rcar-du: Add Color Management Module (CMM)

Hi Eugeniu,

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.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds


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