On Fri January 25 2013 10:51:57 Hans de Goede wrote: > <modified the CC list to be more appropriate> > > Hi, > > On 12/25/2012 05:56 AM, Mauro Carvalho Chehab wrote: > > > The pwc driver can currently return -ENOENT at VIDIOC_S_FMT ioctl. This > > doesn't seem right. Instead, it should be getting the closest format to > > the requested one and return 0, passing the selected format back to > > userspace, just like the other drivers do. I'm c/c Hans de Goede for him > > to take a look on it. > > I've been looking into this today, and the ENOENT gets returned by > pwc_set_video_mode and through that by: > 1) Device init > 2) VIDIOC_STREAMON > 3) VIDIOC_S_PARM > 4) VIDIOC_S_FMT > > But only when the requested width + height + pixelformat is an > unsupported combination, and it being a supported combination > already gets enforced by a call to pwc_get_size in > pwc_vidioc_try_fmt, which also gets called from pwc_s_fmt_vid_cap > before it does anything else. > > So the ENOENT can only happen on some internal driver error, > I'm open for suggestions for a better error code to return in > this case. Perhaps returning EINVAL but adding a WARN_ON would be a good compromise. > What I did notice is that pwc_vidioc_try_fmt returns EINVAL when > an unsupported pixelformat is requested. IIRC we agreed that the > correct behavior in this case is to instead just change the > pixelformat to a default format, so I'll write a patch fixing > this. There are issues with that idea in the case of TV capture cards, since some important apps (tvtime and mythtv to a lesser extent) assume -EINVAL in the case of unsupported pixelformats. Webcam apps can't assume that since gspca never returned -EINVAL, so I think it should be OK to fix this in pwc, but Mauro may disagree. Regards, Hans -- 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
