Date: Sat, 11 Mar 2017 18:51:37 +0000
From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Steve Longerbeam <slongerbeam@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>, robh+dt@kernel.org,
        mark.rutland@arm.com, shawnguo@kernel.org, kernel@pengutronix.de,
        fabio.estevam@nxp.com, mchehab@kernel.org, nick@shmanahar.org,
        markus.heiser@darmarIT.de, p.zabel@pengutronix.de,
        laurent.pinchart+renesas@ideasonboard.com, bparrot@ti.com,
        geert@linux-m68k.org, arnd@arndb.de, sudipm.mukherjee@gmail.com,
        minghsiu.tsai@mediatek.com, tiffany.lin@mediatek.com,
        jean-christophe.trotin@st.com, horms+renesas@verge.net.au,
        niklas.soderlund+renesas@ragnatech.se, robert.jarzmik@free.fr,
        songjun.wu@microchip.com, andrew-ct.chen@mediatek.com,
        gregkh@linuxfoundation.org, shuah@kernel.org,
        sakari.ailus@linux.intel.com, pavel@ucw.cz, devel@driverdev.osuosl.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org
Subject: Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event
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On Sat, Mar 11, 2017 at 10:14:49AM -0800, Steve Longerbeam wrote:
> On 03/11/2017 03:39 AM, Hans Verkuil wrote:
> >It's fine to use an internal event as long as the end-user doesn't
> >see it. But if you lose vsyncs, then you never capture another frame,
> >right?
> 
> No, that's not correct. By loss of vertical sync, I mean the IPU
> captures portions of two different frames, resulting in a permanent
> "split image", with one frame containing portions of two consecutive
> images. Or, the video rolls continuously, if you remember the old CRT
> television sets of yore, it's the same rolling effect.

I have seen that rolling effect, but the iMX6 regains correct sync
within one complete "roll" just fine here with IMX219.  However, it
has always recovered.

So, I don't think there's a problem with the iMX6 part of the
processing, and so I don't think we should cripple the iMX6 capture
drivers for this problem.

It seems to me that the problem is with the source.

-- 
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