linux-kernel - Re: [PATCH v2 0/3] Improve error handling in the rcar-vin driver

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Message-ID: <YsQIbr9QYGBDoIWT@oden.dyn.berto.se>
Date:   Tue, 5 Jul 2022 11:46:22 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Michael Rodin <mrodin@...adit-jv.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-renesas-soc@...r.kernel.org, michael@...in.online,
        erosca@...adit-jv.com
Subject: Re: [PATCH v2 0/3] Improve error handling in the rcar-vin driver

Hi Michael,

Thanks for your persistent work with this series.

On 2022-06-28 20:00:19 +0200, Michael Rodin wrote:
> Hello,
> 
> this series is a followup to the other series [1] started by Niklas Söderlund
> where only the first patch has been merged. The overall idea is to be more
> compliant with the Renesas hardware manual which requires a reset or stop
> of capture in the VIN module before reset of CSI2. Another goal is to be
> more resilient with respect to non-critical CSI2 errors so the driver does
> not end in an endless restart loop. Compared to the previous version [2] of
> this series the patch 3 is replaced based on the conclusion in [3] so now
> userspace has to take care of figuring out if a transfer error was harmless
> or unrecoverable. Other patches are adapted accordingly so no assumptions
> about criticality of transfer errors are made in the kernel and the
> decision is left up to userspace.

I like this solution as it truly pushes the decision to user-space. What 
bugs me a little bit is that we don't have a way to communicate errors 
that we know are unrecoverable (it was for this case the work in this 
area started) and ones that could be recoverable (the use-case added on 
top).

I would also like to hear what Hans thinks as he had good suggestions 
for how to handle the cases we know can't be recovers in [4].

> 
> [1] https://lore.kernel.org/linux-renesas-soc/20211108160220.767586-1-niklas.soderlund+renesas@ragnatech.se/
> [2] https://lore.kernel.org/all/1652983210-1194-1-git-send-email-mrodin@de.adit-jv.com/
> [3] https://lore.kernel.org/all/YqEO3%2FKekkZhVjW+@oden.dyn.berto.se/

4. https://lore.kernel.org/all/1fddc966-5a23-63b4-185e-c17aa6d65b54@xs4all.nl/

-- 
Kind Regards,
Niklas Söderlund