Hi On Thu, Sep 11, 2014 at 3:06 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Thu, Sep 11, 2014 at 02:22:55PM +0200, David Herrmann wrote: >> actual-brightness is a bit more tricky. Currently, DRM caches property >> values, so there is no read_property() hook. We'd have to add this. >> But it'll be quite nasty as we have to call into the backlight driver. >> So I think we want to run an async-interruptible worker on the >> backlight, drop the locks in the ioctl and wait for the job to finish. >> Not sure whether it's worth it.. maybe we can add this later. > > See Jani's reply - we probably don't need it, at least not in version 1. I couldn't see any comment regarding "actual-brightness". But I'm totally fine with dropping this. >> >> > - How does udev match on the drm connector name? They are not terribly >> > stable atm, and if you reload your drm driver, or much more likely, have >> > two gpus with two drm drivers they change. We probably should change the >> > name allocation scheme to be per device instance instead of global >> > first. Within a driver probe order is hopefully deterministic on a given >> > platform, since even with super dynamic setups (based on dt/acpi) the >> > firmware tables should change really. >> >> You can match on EDID attributes. Ok, so far this is pretty ugly as >> the EDID property is binary. But we can add rather trivial udev >> extensions to make EDID binary against text matching possible. > > Why EDID? This is purely about the drm connector name, e.g. if I have 2 > gpus, both with an eDP connector (optimus, so just one panel) then the > first driver gets eDP-1 as the name of it and the 2nd one eDP-2. Which is > ok if both should control backlight brightness through the same driver, > but a total mess if not just gpus get switched, but also backlight > controllers. > > And if you reload you get then eDP-2 and eDP-3. Well at least in the past, > that hilarity at least was fixed in > > commit b21e3afe2357c0f49348a5fb61247012bf8262ec > Author: Ilia Mirkin <imirkin@xxxxxxxxxxxx> > Date: Wed Aug 7 22:34:48 2013 -0400 > > drm: use ida to allocate connector id > > What I think we need to do is to make these ida allocators per-device, so > that both drivers have an eDP-1 connector. Otherwise you need to either > match both or do funny tricks like "the first eDP connector, no matter > which one on this gpu". After all we can now support more than one eDP > (and more than one LVDS since a long time actually). > > Or how exactly is the udev hw db supposed to match this stuff for special > cases. In general we need to duplicate the existing logic from > libbacklight, like Matthew suggested. Yeah, I get what you mean. Names are not stable so even if we can match on the internal card, we cannot match on "lowest available eDP display". per-device IDs should be totally fine and fix this issue. We prefix connectors with the device name anyway, so no conflicts can arise. But I think we want to make this a udev builtin anyway. So we can easily implement the same logic as libbacklight. Thanks David _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
