On Tue, Jun 25, 2019 at 02:36:39PM +0100, Emil Velikov wrote: > On 2019/06/25, Andrzej Pietrasiewicz wrote: > > Hi Russell, > > > > W dniu 25.06.2019 o 12:03, Russell King - ARM Linux admin pisze: > > > On Tue, Jun 25, 2019 at 11:46:34AM +0200, Andrzej Pietrasiewicz wrote: > > > > It is difficult for a user to know which of the i2c adapters is for which > > > > drm connector. This series addresses this problem. > > > > > > > > The idea is to have a symbolic link in connector's sysfs directory, e.g.: > > > > > > > > ls -l /sys/class/drm/card0-HDMI-A-1/i2c-2 > > > > lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/i2c-2 \ > > > > -> ../../../../soc/13880000.i2c/i2c-2 > > > > > > Don't you want the symlink name to be "i2c" or something fixed, rather > > > than the name of the i2c adapter? Otherwise, you seem to be encumbering > > > userspace with searching the directory to try and find the symlink. > > > > > > > Thank you for your comment. So you imagine something on the lines of: > > > > lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \ > > -> ../../../../soc/13880000.i2c/i2c-2 > > > > ? > > > Fwiw my Intel machine lists a number of i2c devices: > /sys/class/drm/card0-DP-1/i2c-6 > /sys/class/drm/card0-DP-2/i2c-7 > /sys/class/drm/card0-eDP-1/i2c-5 > > Note: I haven't looked _if_ they relate to ones you're proposing here. > > One thing worth mentioning is, the ones I've seen are not symlinks to > another sysfs entries. And there aren't any i2c nodes in /dev ... > > Just a random food for thought :-) Those are the i2c-over-dp-aux controllers. I think we want to list these too. Btw to make this more useful maybe some default implementations for get_modes which automatically dtrt, as a helper? Probably could use that to squash quite a bit of boilerplate. Otherwise I like this. Biggest problem I'm seeing here is rolling this out everywhere, this is a lot of work. And without widespread adoptions it's not terribly useful for userspace. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
