Message-ID: <1490018451.2917.86.camel@pengutronix.de>
Subject: Re: [PATCH v5 38/39] media: imx: csi: fix crop rectangle reset in
 sink set_fmt
From: Philipp Zabel <p.zabel@pengutronix.de>
To: Russell King - ARM Linux <linux@armlinux.org.uk>
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>
Date: Mon, 20 Mar 2017 15:00:51 +0100
In-Reply-To: <20170320120855.GH21222@n2100.armlinux.org.uk>
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On Mon, 2017-03-20 at 12:08 +0000, Russell King - ARM Linux wrote:
> On Mon, Mar 20, 2017 at 12:55:26PM +0100, Philipp Zabel wrote:
> > The above paragraph suggests we skip any rectangles that are not
> > supported. In our case that would be 3. and 4., since the CSI can't
> > compose into a larger frame. I hadn't realised that the crop selection
> > currently happens on the source pad.
> 
> I'd recommend viewing the documentation in its post-processed version,
> because then you get the examples as pictures, and they say that a
> picture is worth 1000 words.  See
> 
>   https://linuxtv.org/downloads/v4l-dvb-apis/uapi/v4l/dev-subdev.html
> 
> There is almost an exact example of what we're trying to do - it's
> figure 4.6.  Here, we have a sink pad with a cropping rectangle on
> the input, which is then scaled to a composition rectangle (there's
> no bounds rectangle, and it's specified that in such a case the
> top,left of the composition rectangle will always be 0,0 - see quote
> below).
> 
> Where it differs is that the example also supports source cropping
> for two source pads.  We don't support that.
>
> 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.

regards
Philipp