Em Sun, 06 Jan 2013 13:34:53 +0100 Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx> escreveu: > On 01/06/2013 12:32 PM, Mauro Carvalho Chehab wrote: > > Em Fri, 04 Jan 2013 23:39:12 +0100 > > Sylwester Nawrocki<sylvester.nawrocki@xxxxxxxxx> escreveu: > > > > > >>> Tomasz Stanislawski (1): > >>> s5p-tv: mixer: fix handling of VIDIOC_S_FMT > > > > I'll drop this one for now. Devin raised a point: such changes would break > > existing applications. > > > > So, we'll need to revisit this topic before changing the drivers. > > > > Btw, I failed to find the corresponding patch at patchwork: > > http://patchwork.linuxtv.org/project/linux-media/list/?state=*&q=VIDIOC_S_FMT > > > > So, its status update may be wrong after flushing your pwclient commands. > > Hmm, I got this patch from Tomasz by e-mail and added it to the pull > request. > I think it wasn't sent to the mailing list, but I noticed it only after > sending you the pull requests, when was preparing the pwclient commands. > I've just posted it now, sorry. The link is here: > http://patchwork.linuxtv.org/patch/16143 > > Tomasz created this patch specifically for the purpose of format negotiation > in video pipeline in the application we used to test various scenarios with > DMABUF. I agree this patch has a potential of breaking buggy user space > applications. I can't see other solution for it right now, there seems even > to be no possibility to return some flag in VIDIOC_S_FMT indicating that > format has been modified and is valid, when -EINVAL was returned. This > sounds > ugly anyway, but could ensure backward compatibility for applications that > exppect EINVAL when format has been changed. BTW, I wonder if it is only > fourcc, > or other format parameters as well - like width, height, some applications > expect to get EINVAL when those have changed. The patch makes the driver compliant to v4l-compilance, as its behavior asks for such change, after some discussions we had this year in San Diego. At that time, we all believed that such change were safe. However, we can't do it like proposed there (and on other patches from Hans). The fact is that tvtime and mythtv applications (maybe more) will fail if the returned format is different than the requested ones, as they don't check for the returned value. As no regressions on userspace are allowed, we need to re-discuss this issue. While this doesn't happen, I'll postpone such patches. Comments/suggestions are welcome. Regards, Mauro -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
