Date: Mon, 20 Mar 2017 14:17:05 +0000
From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Steve Longerbeam <slongerbeam@gmail.com>, robh+dt@kernel.org,
        mark.rutland@arm.com, shawnguo@kernel.org, kernel@pengutronix.de,
        fabio.estevam@nxp.com, mchehab@kernel.org, hverkuil@xs4all.nl,
        nick@shmanahar.org, markus.heiser@darmarIT.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, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-media@vger.kernel.org, devel@driverdev.osuosl.org,
        Steve Longerbeam <steve_longerbeam@mentor.com>
Subject: Re: [PATCH v5 38/39] media: imx: csi: fix crop rectangle reset in
 sink set_fmt
Message-ID: <20170320141705.GL21222@n2100.armlinux.org.uk>
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On Mon, Mar 20, 2017 at 03:00:51PM +0100, Philipp Zabel wrote:
> On Mon, 2017-03-20 at 12:08 +0000, Russell King - ARM Linux wrote:
> > The same document says:
> > 
> >   Scaling support is optional. When supported by a subdev, the crop
> >   rectangle on the subdev's sink pad is scaled to the size configured
> >   using the
> >   :ref:`VIDIOC_SUBDEV_S_SELECTION <VIDIOC_SUBDEV_G_SELECTION>` IOCTL
> >   using ``V4L2_SEL_TGT_COMPOSE`` selection target on the same pad. If the
> >   subdev supports scaling but not composing, the top and left values are
> >   not used and must always be set to zero.
> 
> Right, this sentence does imply that when scaling is supported, there
> must be a sink compose rectangle, even when composing is not.
> 
> I have previously set up scaling like this:
> 
> media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080@1/60]"
> media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540@1/30]"
> 
> Does this mean, it should work like this instead?
> 
> media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080@1/60]"
> media-ctl --set-v4l2 "'ipu1_csi0':0[fmt:UYVY2X8/1920x1080@1/60,compose:(0,0)/960x540]"
> media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540@1/30]"
> 
> I suppose setting the source pad format should not be allowed to modify
> the sink compose rectangle.

That is what I believe having read these documents several times, but
we need v4l2 people to confirm.

Note that setting the format on 'ipu1_csi0':0 should already be done by
the previous media-ctl command, so it should be possible to simplify
that to:

media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY2X8/1920x1080@1/60]"
media-ctl --set-v4l2 "'ipu1_csi0':0[compose:(0,0)/960x540]"
media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/960x540@1/30]"

I have tripped over a bug in media-ctl when specifying both a crop and
compose rectangle - the --help output suggests that "," should be used
to separate them.  media-ctl rejects that, telling me the character at
the "," should be "]".  Replacing the "," with " " allows media-ctl to
accept it and set both rectangles, so it sounds like a parser bug - I've
not looked into this any further yet.

-- 
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