On 03/02/2021 06:25, Sebastian Fricke wrote: > Hey Hans, > > I have tested your patch with the same routine, that we've discussed in > the previous mail series. Here are the results: > https://paste.debian.net/1183755/ > > You probably still have to adjust the compliance tool, right? That's correct. I'm waiting for this to get the OK before I work on v4l-utils. > > Here is how the media_dev node looks like for me: > ``` > basti@nanopct4:~$ cat /sys/class/video4linux/v4l-subdev3/media_dev > 240:0 > # corresponds to: > basti@nanopct4:~$ ls -l /dev/ > ... > crw-rw---- 1 root video 240, 0 Feb 3 06:10 media0 > ... > # leads to: > basti@nanopct4:~$ cat /sys/dev/char/240:0/model > rkisp1 Nice. Regards, Hans > ``` > > Greetings and thank you, > Sebastian > > On 02.02.2021 15:49, Hans Verkuil wrote: >> A long standing issue is how to find the associated media device for >> a V4L or DVB device node. This is primarily useful for applications >> like v4l2-ctl and v4l2-compliance. >> >> Until recently these applications relied on /sys and the fact that >> the media device was accessible in /sys via: >> >> /sys/class/video4linux/videoX/device/mediaY/ >> >> But commit ee494cf377e1 ("media: v4l2-device: Link subdevices to their >> parent devices if available") broke that scheme for subdevices. That >> scheme was rather a hack anyway. >> >> Attempts to report the major/minor number of the media device via the >> public API (i.e. by extending VIDIOC_QUERYCAP or VIDIOC_SUBDEV_QUERYCAP) >> failed, so this patch series now just adds a media_dev attribute when a >> V4L or DVB device node is created. This attribute contains the major:minor >> of the media device. It is only created if the device node is actually >> associated with a media controller. >> >> The original idea for this v3 was to store the media device minor/major >> at the time of the device node registration, however the media device >> node is typically created last, so this information isn't known yet. >> >> Instead a new media_device_devt() function was added that returns the >> dev_t of the media device node safely. >> >> In addition a patch was added for vim2m to ensure that the v4l2_dev.mdev >> is set before video_register_device() to ensure that the media_dev >> attribute is created. >> >> This issue was reported by Sebastian Frick: >> >> https://lore.kernel.org/linux-media/20210120183054.5ltnjdtrmumplevt@basti-TUXEDO-Book-XA1510/T/#t >> >> Regards, >> >> Hans >> >> Changes since v2: add new media_device_devt function. >> Add vim2m patch: v4l2_dev.mdev was set too late. >> >> Changes since v1: use the is_visible callback to ensure the attribute >> is only shown if mdev is non-NULL. >> >> Hans Verkuil (4): >> vim2m: intialize the media device earlier >> media-device: add media_device_devt function >> v4l2-dev: add /sys media_dev attr for V4L2 devices >> dvbdev: add /sys media_dev attr for DVB devices >> >> drivers/media/dvb-core/dvbdev.c | 45 +++++++++++++++++++++++++++ >> drivers/media/mc/mc-device.c | 16 ++++++++++ >> drivers/media/test-drivers/vim2m.c | 14 +++++---- >> drivers/media/v4l2-core/v4l2-dev.c | 49 +++++++++++++++++++++++++++++- >> include/media/media-device.h | 10 ++++++ >> 5 files changed, 127 insertions(+), 7 deletions(-) >> >> -- >> 2.29.2 >>
