[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 at linux-m68k.org>
Sent: Mittwoch, 27. Mai 2020 09:35
To: REE erosca at DE.ADIT-JV.COM <erosca at DE.ADIT-JV.COM>
Cc: Jacopo Mondi <jacopo+renesas at jmondi.org>; Laurent Pinchart <laurent.pinchart at ideasonboard.com>; Kieran Bingham <kieran.bingham+renesas at ideasonboard.com>; Simon Horman <horms at verge.net.au>; Ulrich Hecht <uli+renesas at fpond.eu>; VenkataRajesh.Kalakodima at in.bosch.com; David Airlie <airlied at linux.ie>; Daniel Vetter <daniel at ffwll.ch>; KOJI MATSUOKA <koji.matsuoka.xm at renesas.com>; muroya at ksk.co.jp; Harsha.ManjulaMallikarjun at in.bosch.com; Ezequiel Garcia <ezequiel at collabora.com>; Sean Paul <seanpaul at chromium.org>; Linux-Renesas <linux-renesas-soc at vger.kernel.org>; DRI Development <dri-devel at lists.freedesktop.org>; Linux Kernel Mailing List <linux-kernel at vger.kernel.org>; Michael Dege <michael.dege at renesas.com>; Gotthard Voellmeke <gotthard.voellmeke at renesas.com>; REE efriedrich at DE.ADIT-JV.COM <efriedrich at DE.ADIT-JV.COM>; Michael Rodin <mrodin at de.adit-jv.com>; ChaitanyaKumar.Borah at in.bosch.com; Eugeniu Rosca <roscaeugeniu at gmail.com>
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 at de.adit-jv.com> 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 at linux-m68k.org

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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