On Thu, 07 Jan 2016, Daniel Vetter <daniel@xxxxxxxx> wrote:
> On Thu, Jan 07, 2016 at 10:15:00AM +0200, Jani Nikula wrote:
>> On Wed, 06 Jan 2016, Matt Roper <matthew.d.roper@xxxxxxxxx> wrote:
>> > Our attempts save/restore panel power state in i915_suspend.c are
>> > causing unclaimed register warnings on BXT since the registers for this
>> > platform differ from older platforms.
>> >
>> > The big hammer suspend/resume shouldn't be necessary for PP since the
>> > connector/encoder hooks should already handle this. In theory we could
>> > remove this for all platforms, but in practice it's likely that would
>> > cause some regressions since older platforms with LVDS may have
>> > incomplete PP handling. For now we'll leave the PCH save/restore alone
>> > and change the non-PCH branch to only operate on gen <= 4 so that BXT
>> > and future platforms aren't included.
>> >
>> > v2: Typo fix: s/||/&&/
>> >
>> > v3: Change non-PCH condition to a gen <= 4 test rather than listing
>> > VLV/CHV/BXT as specific platforms to exclude; should be more
>> > future-proof as we add new platforms. (Daniel)
>> >
>> > Cc: Vandana Kannan <vandana.kannan@xxxxxxxxx>
>> > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
>> > Cc: Daniel Vetter <daniel@xxxxxxxx>
>> > Cc: drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx
>> > Signed-off-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
>> > ---
>> > Although it's the direction we want to move, I'm not brave enough to blow away
>> > the entire PP save/restore for all platforms since I don't have the HW
>> > necessary to deal with the regressions that might pop up. The consensus on IRC
>> > is that there probably will be a few regressions when we do that, so I'd rather
>> > have people with appropriate platform access make those changes.
>>
>> This is the first step we want to take anyway.
>>
>> Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>
> Just looked at this some more, and the code here is the only code that
> restores PP registers. Except for vlv/chv, where we have a call to
> intel_dp_init_panel_power_sequencer_registers in vlv_power_sequencer_pipe.
>
> I think we first need to sprinkle more calls to restore PP registers
> around before we can disable this here for bxt. This patch here just
> papers over a legit bug, without fixing it really.
No, this patch doesn't paper over anything. The code that gets run for
Broxton before this patch doesn't save/restore any meaningful registers
that could possibly help with PP. This fixes unclaimed register
read/writes, and it's a valid fix as such.
The commit message should probably be fixed to say that we're not there
yet for Broxton with the hooks. But IMO this patch is a valid fix and
orthogonal to the issue of fixing the hooks.
BR,
Jani.
> -Daniel
>
>>
>>
>>
>> >
>> > drivers/gpu/drm/i915/i915_suspend.c | 4 ++--
>> > 1 file changed, 2 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
>> > index a2aa09c..a8af594 100644
>> > --- a/drivers/gpu/drm/i915/i915_suspend.c
>> > +++ b/drivers/gpu/drm/i915/i915_suspend.c
>> > @@ -49,7 +49,7 @@ static void i915_save_display(struct drm_device *dev)
>> > dev_priv->regfile.savePP_ON_DELAYS = I915_READ(PCH_PP_ON_DELAYS);
>> > dev_priv->regfile.savePP_OFF_DELAYS = I915_READ(PCH_PP_OFF_DELAYS);
>> > dev_priv->regfile.savePP_DIVISOR = I915_READ(PCH_PP_DIVISOR);
>> > - } else if (!IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev)) {
>> > + } else if (INTEL_INFO(dev)->gen <= 4) {
>> > dev_priv->regfile.savePP_CONTROL = I915_READ(PP_CONTROL);
>> > dev_priv->regfile.savePP_ON_DELAYS = I915_READ(PP_ON_DELAYS);
>> > dev_priv->regfile.savePP_OFF_DELAYS = I915_READ(PP_OFF_DELAYS);
>> > @@ -84,7 +84,7 @@ static void i915_restore_display(struct drm_device *dev)
>> > I915_WRITE(PCH_PP_OFF_DELAYS, dev_priv->regfile.savePP_OFF_DELAYS);
>> > I915_WRITE(PCH_PP_DIVISOR, dev_priv->regfile.savePP_DIVISOR);
>> > I915_WRITE(PCH_PP_CONTROL, dev_priv->regfile.savePP_CONTROL);
>> > - } else if (!IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev)) {
>> > + } else if (INTEL_INFO(dev)->gen <= 4) {
>> > I915_WRITE(PP_ON_DELAYS, dev_priv->regfile.savePP_ON_DELAYS);
>> > I915_WRITE(PP_OFF_DELAYS, dev_priv->regfile.savePP_OFF_DELAYS);
>> > I915_WRITE(PP_DIVISOR, dev_priv->regfile.savePP_DIVISOR);
>>
>> --
>> Jani Nikula, Intel Open Source Technology Center
--
Jani Nikula, Intel Open Source Technology Center
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