lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sat, 18 Feb 2017 18:08:44 +0000 From: Russell King - ARM Linux <linux@...linux.org.uk> To: Steve Longerbeam <slongerbeam@...il.com> Cc: robh+dt@...nel.org, mark.rutland@....com, shawnguo@...nel.org, kernel@...gutronix.de, fabio.estevam@....com, mchehab@...nel.org, hverkuil@...all.nl, nick@...anahar.org, markus.heiser@...marIT.de, p.zabel@...gutronix.de, laurent.pinchart+renesas@...asonboard.com, bparrot@...com, geert@...ux-m68k.org, arnd@...db.de, sudipm.mukherjee@...il.com, minghsiu.tsai@...iatek.com, tiffany.lin@...iatek.com, jean-christophe.trotin@...com, horms+renesas@...ge.net.au, niklas.soderlund+renesas@...natech.se, robert.jarzmik@...e.fr, songjun.wu@...rochip.com, andrew-ct.chen@...iatek.com, gregkh@...uxfoundation.org, shuah@...nel.org, sakari.ailus@...ux.intel.com, pavel@....cz, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org, devel@...verdev.osuosl.org Subject: Re: [PATCH v4 29/36] media: imx: mipi-csi2: enable setting and getting of frame rates On Sat, Feb 18, 2017 at 09:29:17AM -0800, Steve Longerbeam wrote: > On 02/18/2017 01:23 AM, Russell King - ARM Linux wrote: > >On Fri, Feb 17, 2017 at 05:12:44PM -0800, Steve Longerbeam wrote: > >>Hi Russell, > >> > >>I signed-off on this but after more review I'm not sure this is right. > >> > >>The CSI-2 receiver really has no control over frame rate. It's output > >>frame rate is the same as the rate that is delivered to it. > >> > >>So this subdev should either not implement these ops, or it should > >>refer them to the attached source subdev. > > > >Where in the V4L2 documentation does it say that is permissible? > > > > https://www.linuxtv.org/downloads/v4l-dvb-apis-old/vidioc-subdev-g-frame-interval.html > > "The frame interval only makes sense for sub-devices that can control the > frame period on their own. This includes, for instance, image sensors and TV > tuners. Sub-devices that don't support frame intervals must not implement > these ioctls." That sounds clear - but the TV tuner example seems odd - the frame rate is determined at transmission time, not reception time. Yes, it's possible to skip frames (which would be scaling) but you can't _control_ the frame rate per se. > >If you don't implement these, media-ctl fails to propagate _anything_ > >to the next sink pad if you specify a frame rate, because media-ctl > >throws an error and exits immediately. > > > > But I agree with you here. I think our only option is to ignore that > quoted requirement above and propagate [gs]_frame_interval all the way > to the CSI (which can control the frame rate via frame skipping). Sounds like something to tackle the media maintainers over - the documentation vs media-ctl seem to have different ideas on this point. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.
Powered by blists - more mailing lists