[PATCH v2 2/2] drm/i915/psr: check drm_mode_vrefresh return value

[Hogander, Jouni]

On Thu, 2025-08-21 at 16:10 +0300, Ville Syrjälä wrote:
> On Thu, Aug 21, 2025 at 07:59:18AM +0300, Jouni Högander wrote:
> > Check drm_mode_vrefresh return value sanity before using it in
> > intel_get_frame_time_us.
> > 
> > Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_psr.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> > b/drivers/gpu/drm/i915/display/intel_psr.c
> > index 5addde63168e..8cc2314fac6f 100644
> > --- a/drivers/gpu/drm/i915/display/intel_psr.c
> > +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> > @@ -1116,11 +1116,16 @@ transcoder_has_psr2(struct intel_display
> > *display, enum transcoder cpu_transcode
> >  
> >  static u32 intel_get_frame_time_us(const struct intel_crtc_state
> > *crtc_state)
> >  {
> > +	int vrefresh;
> > +
> >  	if (!crtc_state->hw.active)
> >  		return 0;
> >  
> > -	return DIV_ROUND_UP(1000 * 1000,
> > -			    drm_mode_vrefresh(&crtc_state-
> > >hw.adjusted_mode));
> > +	vrefresh = drm_mode_vrefresh(&crtc_state-
> > >hw.adjusted_mode);
> > +	if (vrefresh <= 0)
> 
> How would that happen?

There are some sanity checks in drm_mode_vrefresh returning 0. Do you
think we should just rely on that we would not end up here with such
broken drm mode data?

BR,

Jouni Högander
> 
> > +		return 0;
> > +
> > +	return DIV_ROUND_UP(1000 * 1000, vrefresh);
> >  }
> >  
> >  static void psr2_program_idle_frames(struct intel_dp *intel_dp,
> > -- 
> > 2.43.0
>