On Mon, Apr 25, 2016 at 08:25:14PM +0300, Ville Syrjälä wrote:
> On Sun, Apr 24, 2016 at 07:10:19PM +0100, Chris Wilson wrote:
> > Both execlists and legacy need to reset the context (and mode) of the
> > GPU before we lose control of the system. By resetting the GPU, we
> > revert back to default settings. This simplifies the life of any
> > subsequent driver (in particular for virtualized setups) as it does not
> > then have to try and recover from an unknown condition. As both paths
> > need to reset for the same reason, move the reset to a common point.
> >
> > This unifies the resets added in a647828afc (drm/i915: Also perform gpu
> > reset under execlist mode) and 8e96d9c4d9 (drm/i915: reset the GPU on
> > context fini).
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
> > CC: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> > Cc: "Niu, Bing" <bing.niu@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/i915_dma.c | 41 ++++++++++++++++++++++++++-------
> > drivers/gpu/drm/i915/i915_gem.c | 8 -------
> > drivers/gpu/drm/i915/i915_gem_context.c | 8 +------
> > 3 files changed, 34 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> > index 5c7615041b31..68c60f4fd44d 100644
> > --- a/drivers/gpu/drm/i915/i915_dma.c
> > +++ b/drivers/gpu/drm/i915/i915_dma.c
> > @@ -425,6 +425,37 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
> > .can_switch = i915_switcheroo_can_switch,
> > };
> >
> > +static void i915_gem_fini(struct drm_device *dev)
> > +{
> > + int reset;
> > +
> > + /*
> > + * Neither the BIOS, ourselves or any other kernel
> > + * expects the system to be in execlists mode on startup,
> > + * so we need to reset the GPU back to legacy mode. And the only
> > + * known way to disable logical contexts is through a GPU reset.
> > + *
> > + * So in order to leave the system in a known default configuration,
> > + * always reset the GPU upon unload. Afterwards we then clean up the
> > + * GEM state tracking, flushing off the requests and leaving the
> > + * system in a known idle state.
> > + *
> > + * Note that is of the upmost importance that the GPU is idle and
> > + * all stray writes are flushed *before* we dismantle the backing
> > + * storage for the pinned objects.
> > + */
> > + reset = intel_gpu_reset(dev, ALL_ENGINES);
>
> That's going to kill pre-g4x macines I think. At least until Maarten's
> reset locking fixes go in. Even then I'm not sure we want to do that on
> those old machines.
Reset locking in shutdown? intel_gpu_reset() is just the register poke.
We can limit it to say gen5 to be safe?
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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