[PATCH v3 2/4] drm/i915/display: don't allow DMC wakelock on older hardware

[Luca Coelho]

On Thu, 2024-03-21 at 08:02 +0000, Shankar, Uma wrote:
> 
> > -----Original Message-----
> > From: Coelho, Luciano <luciano.coelho at intel.com>
> > Sent: Monday, March 18, 2024 7:08 PM
> > To: intel-gfx at lists.freedesktop.org
> > Cc: intel-xe at lists.freedesktop.org; Shankar, Uma <uma.shankar at intel.com>;
> > ville.syrjala at linux.intel.com; Nikula, Jani <jani.nikula at intel.com>
> > Subject: [PATCH v3 2/4] drm/i915/display: don't allow DMC wakelock on older
> > hardware
> > 
> > Only allow running DMC wakelock code if the display version is 20 or greater.
> 
> One for previous one, don't do intel_dmc_wl_init unconditionally but protect it with
> Platform check.

Good point.  I have removed the call to intel_dmc_wl_init() completely
from the previous patch, like with intel_dmc_wl_enable(), so the call
to init will be in this patch and protected by the platform version as
well.


> > Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dmc_wl.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_dmc_wl.c
> > b/drivers/gpu/drm/i915/display/intel_dmc_wl.c
> > index 5c3d8204ae7e..7c991e22c616 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dmc_wl.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dmc_wl.c
> > @@ -120,6 +120,9 @@ void intel_dmc_wl_enable(struct drm_i915_private
> > *i915)
> >  	struct intel_dmc_wl *wl = &i915->display.wl;
> >  	unsigned long flags;
> > 
> > +	if (DISPLAY_VER(i915) < 20)
> > +		return;
> > +
> >  	spin_lock_irqsave(&wl->lock, flags);
> > 
> >  	if (wl->enabled)
> > @@ -143,6 +146,9 @@ void intel_dmc_wl_disable(struct drm_i915_private
> > *i915)
> >  	struct intel_dmc_wl *wl = &i915->display.wl;
> >  	unsigned long flags;
> > 
> > +	if (DISPLAY_VER(i915) < 20)
> > +		return;
> 
> There can be case where DMC is not loaded, address that as well.
> We should not do wakelock in that case.

Right.  I have added a helper function, intel_dmc_wl_supported(), to
keep all this checks in one place.


> >  	flush_delayed_work(&wl->work);
> > 
> >  	spin_lock_irqsave(&wl->lock, flags);
> > @@ -171,6 +177,9 @@ void intel_dmc_wl_get(struct drm_i915_private *i915,
> > i915_reg_t reg)
> >  	struct intel_dmc_wl *wl = &i915->display.wl;
> >  	unsigned long flags;
> > 
> > +	if (DISPLAY_VER(i915) < 20)
> > +		return;
> > +
> >  	if (!intel_dmc_wl_check_range(reg.reg))
> >  		return;
> > 
> > @@ -203,6 +212,9 @@ void intel_dmc_wl_put(struct drm_i915_private *i915,
> > i915_reg_t reg)
> >  	struct intel_dmc_wl *wl = &i915->display.wl;
> >  	unsigned long flags;
> > 
> > +	if (DISPLAY_VER(i915) < 20)
> > +		return;
> > +
> >  	if (!intel_dmc_wl_check_range(reg.reg))
> >  		return;
> > 
> > --
> > 2.39.2
> 

--
Cheers,
Luca.