On Wed, Feb 07, 2018 at 04:41:43PM +0200, Ville Syrjälä wrote:
> On Wed, Feb 07, 2018 at 10:08:45AM +0000, Chris Wilson wrote:
> > After we assert the reset request (and wait for 20us), when the device
> > has been fully reset it asserts the reset-status bit. Before we stop
> > requesting the reset and allow the device to return to normal, we should
> > wait for the reset to be completed. (Similar to how we wait for the
> > device to return to normal after deasserting the reset request.)
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_uncore.c | 12 ++++++++++--
> > 1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> > index 612aad205b59..dd86428774da 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > @@ -1555,19 +1555,27 @@ static bool i915_reset_complete(struct pci_dev *pdev)
> > u8 gdrst;
> >
> > pci_read_config_byte(pdev, I915_GDRST, &gdrst);
> > - return (gdrst & GRDOM_RESET_STATUS) == 0;
> > + return gdrst & GRDOM_RESET_STATUS;
Doh. Failed to notice this change. The function name is perhaps a bit
confusing now since it doesn't match the meaning of the g4x version.
Maybe rename this guy? i915_gpu_in_reset() or something?
> > }
> >
> > static int i915_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> > {
> > struct pci_dev *pdev = dev_priv->drm.pdev;
> > + int err;
> >
> > /* assert reset for at least 20 usec */
> > pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
> > usleep_range(50, 200);
> > +
> > + err = wait_for(i915_reset_complete(pdev), 500);
>
> The hardware should indicate that it's in reset as long as we keep the
> reset asserted. So this looks like an obfuscated usleep(500) to me.
> Did you mean !reset_complete?
>
> > +
> > pci_write_config_byte(pdev, I915_GDRST, 0);
> > + usleep_range(50, 200);
> > +
> > + if (!err)
> > + err = wait_for(!i915_reset_complete(pdev), 500);
> >
> > - return wait_for(i915_reset_complete(pdev), 500);
> > + return err;
> > }
> >
> > static bool g4x_reset_complete(struct pci_dev *pdev)
> > --
> > 2.16.1
>
> --
> Ville Syrjälä
> Intel OTC
--
Ville Syrjälä
Intel OTC
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