Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752307AbdCSTRZ (ORCPT ); Sun, 19 Mar 2017 15:17:25 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:36250 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751830AbdCSTRW (ORCPT ); Sun, 19 Mar 2017 15:17:22 -0400 Subject: Re: [PATCH v5 38/39] media: imx: csi: fix crop rectangle reset in sink set_fmt To: Russell King - ARM Linux References: <1489121599-23206-1-git-send-email-steve_longerbeam@mentor.com> <1489121599-23206-39-git-send-email-steve_longerbeam@mentor.com> <20170319152233.GW21222@n2100.armlinux.org.uk> Cc: 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, 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, 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 From: Steve Longerbeam Message-ID: <327d67d9-68c1-7f74-0c0f-f6aee1c4b546@gmail.com> Date: Sun, 19 Mar 2017 12:08:02 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170319152233.GW21222@n2100.armlinux.org.uk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3906 Lines: 88 On 03/19/2017 08:22 AM, Russell King - ARM Linux wrote: > On Thu, Mar 09, 2017 at 08:53:18PM -0800, Steve Longerbeam wrote: >> From: Philipp Zabel >> >> The csi_try_crop call in set_fmt should compare the cropping rectangle >> to the currently set input format, not to the previous input format. > Are we really sure that the cropping support is implemented correctly? > > I came across this while looking at what we're doing with the > V4L2_SEL_FLAG_KEEP_CONFIG flag. > > Documentation/media/uapi/v4l/dev-subdev.rst defines the behaviour of > the user API, and "Order of configuration and format propagation" says: > > The coordinates to a step always refer to the actual size of the > previous step. The exception to this rule is the source compose > rectangle, which refers to the sink compose bounds rectangle --- if it > is supported by the hardware. > > 1. Sink pad format. The user configures the sink pad format. This format > defines the parameters of the image the entity receives through the > pad for further processing. > > 2. Sink pad actual crop selection. The sink pad crop defines the crop > performed to the sink pad format. > > 3. Sink pad actual compose selection. The size of the sink pad compose > rectangle defines the scaling ratio compared to the size of the sink > pad crop rectangle. The location of the compose rectangle specifies > the location of the actual sink compose rectangle in the sink compose > bounds rectangle. > > 4. Source pad actual crop selection. Crop on the source pad defines crop > performed to the image in the sink compose bounds rectangle. > > 5. Source pad format. The source pad format defines the output pixel > format of the subdev, as well as the other parameters with the > exception of the image width and height. Width and height are defined > by the size of the source pad actual crop selection. > > Accessing any of the above rectangles not supported by the subdev will > return ``EINVAL``. Any rectangle referring to a previous unsupported > rectangle coordinates will instead refer to the previous supported > rectangle. For example, if sink crop is not supported, the compose > selection will refer to the sink pad format dimensions instead. > > Note step 3 above: scaling is defined by the ratio of the _sink_ crop > rectangle to the _sink_ compose rectangle. > > So, lets say that the camera produces a 1280x720 image, and the sink > pad format is configured with 1280x720. That's step 1. > > The sink crop operates within that rectangle, cropping it to an area. > Let's say we're only interested in its centre, so we'd chose 640x360 > with the top-left as 320,180. This is step 2. > > Then, if we want to down-scale by a factor of two, we'd set the sink > compose selection to 320x180. > > This seems to be at odds with how the scaling is done in CSI at > present: the selection implementations all reject attempts to > configure the sink pad, instead only supporting crop rectangles on > the source, Correct. Currently cropping is only supported at the source pad (step 4). Initially the CSI didn't support down-scaling, so step 3 is not supported, so the sink pad format/crop selection rectangle/crop compose rectangle are collapsed into the same sink pad format rectangle. Philipp later added support for /2 downscaling, but we didn't put this in the correct API, looks like this needs to move into the selection API at step 3 (sink pad compose rectangle). > and we use the source crop rectangle to define the > down-scaling. Yes. And maybe there is nothing wrong with that, because scaling is also defined by the source/sink _format_ ratios (if I'm not mistaken), so looking at this another way, we're just defining scaling in the CSI via another legal API. Steve