On 20 January 2017 at 16:17, Thierry Reding <treding@xxxxxxxxxx> wrote: > On Fri, Jan 20, 2017 at 02:13:00PM +0000, Emil Velikov wrote: >> On 19 January 2017 at 09:19, Thierry Reding <treding@xxxxxxxxxx> wrote: >> > On Wed, Jan 18, 2017 at 02:59:21PM +0100, Neil Armstrong wrote: >> >> Add support for Amlogic Meson DRM driver merged for Linux 4.10. >> >> >> >> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx> >> >> --- >> >> tests/util/kms.c | 1 + >> >> 1 file changed, 1 insertion(+) >> > >> > Applied, thanks. >> > >> Was going to say "NACK use Thierry's helpers" but you've beat me to it. >> As a Tl;DR: we _really_ want to stop using drmOpen* for anything that's KMS. > > I think it's still useful to have this helper to iterate over all > supported driver because it enables easy testing with just a simple > modetest. > > That said, for (almost) as long as I remember I've been using the -M > option to prevent modetest from iterating over the list, which can take > fairly long if you've got DRM_DEBUG messages enabled. > > I'm not sure I understand exactly what you're suggesting by "use > Thierry's helpers". modetest and other tests use util_open() internally > now. That in turn uses drmOpen(), though we're of course open to change > that. Are you suggesting we somehow use drmDevice to locate existing > devices? > Yes using drmDevice is what I had in mind. The only thing that was stopping me from doing that is the lack of platform devices support. With that in we can start purging _everything_ that uses drmOpen*. > We could implement some heuristic that finds the first device with a > primary node, but what if we want to support the -M option? There is > currently no way of getting the driver from drmDevice. Maybe that's > something we should add anyway. > The -M (kernel module name as given by drmGetVersion) is another interesting topic. Feel free to skip to the Tl;Dr below. If doing the ioctl implicitly via drmOpen or drmDevice wakes up the device, keeping in mind that: - it can take some time, and - you don't always need the info A couple of elaborate workarounds include: - use only on demand - add DRM_DEVICE_GET_MODULE_NAME or alike to the drmDevice2 API Needs a big "this can be VERY slow" warning in the documentation/man pages... first we need actual man pages for libdrm ;-) - deprecate the whole thing and use the compat strings - how do we handle the PCI devices ? - use the kernel module name (foo.ko) - kind of making it an ABI, but iirc we've already have users which depend on it Neither PCI devices nor platform ones are consistent in their naming - foo.ko vs the value returned by the IOCTL. We might be able to combine the latter two ... need to double-check. Tl;Dr: For the moment I'd leave it to the user to call drmGetVersion. Thanks Emil _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
