| Message ID | 20220628180024.451258-1-mrodin@de.adit-jv.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Improve error handling in the rcar-vin driver | expand |
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/
Hi Niklas, Hans, On Tue, Jul 05, 2022 at 11:46:22AM +0200, Niklas Söderlund wrote: > Hi Michael, > > Thanks for your persistent work with this series. Thank you for the feedback! > 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). Yes, it's not nice that V4L2_EVENT_XFER_ERROR does not tell userspace whether an error is recoverable (i.e. the event can be ignored) or not (i.e. a restart of streaming is required) but the other possible option would be (as concluded in [3]) to implement a frame timeout monitoring thread in v4l2 core. I am not sure if it is possible to implement this second option cleanly... > 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]. A a new function vb2_queue_error_with_event() suggested by Hans seems to be redundant now, since it would not be used by rcar-vin (unless we implement frame timeout monitoring in the v4l2 core). Or do you have an idea, which drivers could be the first users of it, e.g. staging/media/imx I mentioned before? > > > > [1] https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_linux-2Drenesas-2Dsoc_20211108160220.767586-2D1-2Dniklas.soderlund-2Brenesas-40ragnatech.se_&d=DwIDAw&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=sWsgk3pKkv5GeIDM2RZlPY8TjNFU2D0oBeOj6QNBadE&m=ecX7IwfatUO7SNPiyQ6x_8K9t2eWJf3y8GNuNHJ_0W0&s=Cli6jADEgMmCOLVoFekRRXzmty9WBXtoSF9utZJNMXY&e= > > [2] https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_all_1652983210-2D1194-2D1-2Dgit-2Dsend-2Demail-2Dmrodin-40de.adit-2Djv.com_&d=DwIDAw&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=sWsgk3pKkv5GeIDM2RZlPY8TjNFU2D0oBeOj6QNBadE&m=ecX7IwfatUO7SNPiyQ6x_8K9t2eWJf3y8GNuNHJ_0W0&s=6CysfSY0OoAenEwCzigeyPOb8vyaa4GgzkJSR-ny83U&e= > > [3] https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_all_YqEO3-252FKekkZhVjW-2B-40oden.dyn.berto.se_&d=DwIDAw&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=sWsgk3pKkv5GeIDM2RZlPY8TjNFU2D0oBeOj6QNBadE&m=ecX7IwfatUO7SNPiyQ6x_8K9t2eWJf3y8GNuNHJ_0W0&s=67JE_QR4x7omrtC7wzbpn2OgW75TAR80-R8WQyE-bVo&e= > > 4. https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_all_1fddc966-2D5a23-2D63b4-2D185e-2Dc17aa6d65b54-40xs4all.nl_&d=DwIDAw&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=sWsgk3pKkv5GeIDM2RZlPY8TjNFU2D0oBeOj6QNBadE&m=ecX7IwfatUO7SNPiyQ6x_8K9t2eWJf3y8GNuNHJ_0W0&s=I18yWgde2UKZY4AiwB5s-Lf12eebHOcHFZFOlTcO2oQ&e= > > -- > Kind Regards, > Niklas Söderlund