On Thu, Feb 16, 2017 at 11:43:06AM +0200, Ander Conselvan De Oliveira wrote:
> On Wed, 2017-02-15 at 13:59 +0200, Imre Deak wrote:
> > Atm, in the power well sync_hw hook we are clearing all BIOS request
> > bits, not just the one corresponding to the given power well. This could
> > turn off an unrelated power well inadvertently if it didn't have a
> > request bit set in the driver request register.
> >
> > This didn't cause a problem so far, since we enabled all power wells
> > explicitly before clearing the BIOS request register. A follow-up
> > patchset will add power wells that won't get enabled this way, so fix up
> > the inconsistency.
> >
> > Cc: Ander Conselvan de Oliveira <conselvan2@xxxxxxxxx>
> > Cc: David Weinehall <david.weinehall@xxxxxxxxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_runtime_pm.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > index f9aff26..b7b0e0f 100644
> > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> > @@ -887,8 +887,13 @@ static bool skl_power_well_enabled(struct drm_i915_private *dev_priv,
> > static void skl_power_well_sync_hw(struct drm_i915_private *dev_priv,
> > struct i915_power_well *power_well)
> > {
> > + uint32_t mask = SKL_POWER_WELL_REQ(power_well->id);
> > + uint32_t bios_req = I915_READ(HSW_PWR_WELL_BIOS);
> > +
> > /* Clear any request made by BIOS as driver is taking over */
> > - I915_WRITE(HSW_PWR_WELL_BIOS, 0);
> > + if (bios_req & mask) {
> > + I915_WRITE(HSW_PWR_WELL_BIOS, bios_req & ~mask);
> > + }
> > }
> >
> > static void skl_power_well_enable(struct drm_i915_private *dev_priv,
>
> With this change we still end up disabling every power well from the BIOS
> register because of intel_power_domains_sync_hw() iterating over all the power
> wells.
Yes, that's what is expected. This patch just changes how this clearing
is done, the next one makes sure we preserve the state for any power
well without a reference.
> Maybe that's worth mentioning in the commit message? Dunno.
Ok, will add something.
> Anyway,
>
> Reviewed-by: Ander Conselvan de Oliveira <conselvan2@xxxxxxxxx>
>
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