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Message-ID: <CAMuHMdVGcFGL6V6_zDCPQA66VFyqM9bQ6choWs8eYfOieFu1ZQ@mail.gmail.com>
Date: Wed, 27 May 2020 09:34:30 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Eugeniu Rosca <erosca@...adit-jv.com>
Cc: Jacopo Mondi <jacopo+renesas@...ndi.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
Simon Horman <horms@...ge.net.au>,
Ulrich Hecht <uli+renesas@...nd.eu>,
VenkataRajesh.Kalakodima@...bosch.com,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Koji Matsuoka <koji.matsuoka.xm@...esas.com>, muroya@....co.jp,
Harsha.ManjulaMallikarjun@...bosch.com,
Ezequiel Garcia <ezequiel@...labora.com>,
Sean Paul <seanpaul@...omium.org>,
Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
DRI Development <dri-devel@...ts.freedesktop.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Michael Dege <michael.dege@...esas.com>,
gotthard.voellmeke@...esas.com, efriedrich@...adit-jv.com,
Michael Rodin <mrodin@...adit-jv.com>,
ChaitanyaKumar.Borah@...bosch.com,
Eugeniu Rosca <roscaeugeniu@...il.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@...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@...ux-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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