linux-kernel - Re: [PATCH] media: renesas: vsp1: blacklist r8a7795 ES1.*

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Message-ID: <Y8f88dw/fWfVij/d@pendragon.ideasonboard.com>
Date:   Wed, 18 Jan 2023 16:06:41 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Wolfram Sang <wsa+renesas@...g-engineering.com>,
        linux-renesas-soc@...r.kernel.org,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: renesas: vsp1: blacklist r8a7795 ES1.*

Hi Geert,

On Wed, Jan 18, 2023 at 03:02:53PM +0100, Geert Uytterhoeven wrote:
> On Wed, Jan 18, 2023 at 2:39 PM Laurent Pinchart wrote:
> > On Wed, Jan 18, 2023 at 02:30:51PM +0100, Geert Uytterhoeven wrote:
> > > On Wed, Jan 18, 2023 at 2:21 PM Laurent Pinchart wrote:
> > > > On Wed, Jan 18, 2023 at 01:20:02PM +0100, Wolfram Sang wrote:
> > > > > The earliest revision of these SoC may hang when underrunning. Later
> > > > > revisions have that fixed. Bail out when we detect a problematic
> > > > > version.
> > > > >
> > > > > Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> > > > > ---
> > > > >
> > > > > The BSP tries to work around the issue, yet this is neither upstreamable
> > > > > nor are we sure the solution is complete. Because the early SoC revision
> > > > > is hardly in use, we simply "document" the problem upstream.
> > > >
> > > > The workaround isn't upstreamable as-is, but I think it could be
> > > > upstreamed after being cleaned up.
> > > >
> > > > Overall, how much support do we still have upstream for H3 ES1.x, and do
> > > > we need to keep it ? H3 ES.1x is relatively old, does someone still rely
> > > > on it ?
> > >
> > > I think the upstream support level for R-Car H3 ES1.x is about the same
> > > as for H3 ES2.0.
> >
> > Question is, do we need to keep it ? :-) And if we do, instead of
> > black-listing devices in the VSP driver, how about dropping them from
> > r8a77950.dtsi ?
> 
> I prefer blacklisting in the driver, as dropping them from r8a77950.dtsi
> wouldn't disable them when used with an older or out-of-tree DTB.

Is that really a use case we need to care about ? Who will run a recent
kernel with an old DTB on a H3 ES1.x, without an easy way to update to a
mainline device tree ? It's not like those devices went into production.

> >  We already delete quite a lot of devices there.
> 
> ... because they don't exist on H3 ES1.x.
> 
> > Note that without VSP support, you will get no display either, so the
> > DU device (and the LVDS encoder) so also be deleted.
> 
> True...

-- 
Regards,

Laurent Pinchart