linux-kernel - Re: [PATCH v4 13/36] [media] v4l2: add a frame timeout event

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Message-ID: <20170305224114.GV21222@n2100.armlinux.org.uk>
Date:   Sun, 5 Mar 2017 22:41:15 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Steve Longerbeam <slongerbeam@...il.com>
Cc:     Sakari Ailus <sakari.ailus@....fi>, mark.rutland@....com,
        andrew-ct.chen@...iatek.com, minghsiu.tsai@...iatek.com,
        sakari.ailus@...ux.intel.com, nick@...anahar.org,
        songjun.wu@...rochip.com, hverkuil@...all.nl,
        Steve Longerbeam <steve_longerbeam@...tor.com>, pavel@....cz,
        robert.jarzmik@...e.fr, devel@...verdev.osuosl.org,
        markus.heiser@...marIT.de,
        laurent.pinchart+renesas@...asonboard.com, shuah@...nel.org,
        geert@...ux-m68k.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, kernel@...gutronix.de, arnd@...db.de,
        mchehab@...nel.org, bparrot@...com, robh+dt@...nel.org,
        horms+renesas@...ge.net.au, tiffany.lin@...iatek.com,
        linux-arm-kernel@...ts.infradead.org,
        niklas.soderlund+renesas@...natech.se, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, jean-christophe.trotin@...com,
        p.zabel@...gutronix.de, fabio.estevam@....com, shawnguo@...nel.org,
        sudipm.mukherjee@...il.com
Subject: Re: [PATCH v4 13/36] [media] v4l2: add a frame timeout event

On Sat, Mar 04, 2017 at 04:37:43PM -0800, Steve Longerbeam wrote:
> 
> 
> On 03/04/2017 02:56 AM, Sakari Ailus wrote:
> >That's a bit of a special situation --- still there are alike conditions on
> >existing hardware. You should return the buffers to the user with the ERROR
> >flag set --- or return -EIO from VIDIOC_DQBUF, if the condition will
> >persist:
> 
> On i.MX an EOF timeout is not recoverable without a stream restart, so
> I decided to call vb2_queue_error() when the timeout occurs (instead
> of sending an event). The user will then get -EIO when it attempts to
> queue or dequeue further buffers.

I'm not sure that statement is entirely accurate.  With the IMX219
camera, I _could_ (with previous iterations of the iMX capture code)
stop it streaming, wait a while, and restart it, and everything
continues to work.

Are you sure that the problem you have here is caused by the iMX6
rather than the ADV718x CVBS decoder (your initial description said
it was the decoder.)

If it _is_ the decoder that's going wrong, that doesn't justify
cripping the rest of the driver for one instance of broken hardware
that _might_ be attached to it.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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