On Fri, Oct 19, 2018 at 09:39:22AM +0100, Chris Wilson wrote: > Quoting Daniel Vetter (2018-10-19 09:22:15) > > On Mon, Oct 15, 2018 at 12:17:41PM +0100, Chris Wilson wrote: > > > If the user passes i915.disable_display=1 we want to disable all the > > > displays and associated HW like the powerwells on their behalf. Instead > > > of short circuiting the HW probe, let it run and setup all the > > > bookkeeping for the known HW. Afterwards, instead of taking over the > > > BIOS fb and installing the fbcon, we shutdown all the outputs and > > > teardown the bookkeeping, leaving us with no attached outputs or crtcs, > > > and all the HW powered down. > > > > > > Open: wq flushes should be required but seem to deadlock the modprobe > > > under CI. > > > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > Cc: Imre Deak <imre.deak@xxxxxxxxx> > > > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > i915.disable_display was for those server chips where doing all the init > > resulted in a dead machine. So not sure we want this. > > For those server chips, we don't use i915.disable_display but detect when > the fuses are lies and directly set num_pipes == 0. If we had such a > machine in CI, you would already have seen a lot of the fun with KMS being > allowed without any backing hw. Hence why Ville suggested we disable KMS > for machines without pipes to avoid having to add a lot of defense > around the driver. > > > What's the issue with power wells still being on and all that? On real hw > > without display they won't exist, and I don't understand why we'd care for > > testing. > > For testing. We do use .disable_display and expect rpm to still work, and > to not get random display related failures interfering in displayless > tests. > > Quite clearly we haven't been testing the displayless setups at all. I definitely like the idea of testing this without requiring special hardware. I guess another way to achieve the result of turning everything off would be to 'modprobe i915 disable_display=0; rmmod i915; modprobe i915 disable_display=1'. That should avoid the need to have a special codepath for shutthing things down. Would that suffice or is there a compelling reason for supporting this without requiring the driver reload? -- Ville Syrjälä Intel _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
