RE: [PATCH 2/2] drm/i915/dmc: Enable PIPEDMC_ERROR interrupt

Kandpal, Suraj
2026-03-13T03:26:52Z

> On 12-03-2026 08:48, Kandpal, Suraj wrote:
> >> Subject: [PATCH 2/2] drm/i915/dmc: Enable PIPEDMC_ERROR interrupt
> >>
> >> Enable PIPEDMC_ERROR interrupt bit for display version 35+.
> >>
> > Add same Bspec link here too
> >
> >> Signed-off-by: Dibin Moolakadan Subrahmanian
> >> <dibin.moolakadan.subrahmanian@intel.com>
> >> ---
> >> drivers/gpu/drm/i915/display/intel_dmc.c | 3 ++-
> >> 1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_dmc.c
> >> b/drivers/gpu/drm/i915/display/intel_dmc.c
> >> index 38b284a0db82..e60f1f977070 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_dmc.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_dmc.c
> >> @@ -510,7 +510,8 @@ static void pipedmc_clock_gating_wa(struct
> >> intel_display *display, bool enable) static u32
> >> pipedmc_interrupt_mask(struct intel_display *display) {
> >> if (DISPLAY_VER(display) >= 35)
> >> - return PIPEDMC_FLIPQ_PROG_DONE;
> >> + return PIPEDMC_FLIPQ_PROG_DONE |
> >> + PIPEDMC_ERROR;
> >>
> > Mostly looks okay but here's my question:
> > I know LNL pipe B had an issue with PIPEDMC_ERROR being triggered on
> > LNL pipe B, As I can see from Ville's commit message, but is it still the case for
> PTL ?
> > Can we have that tested ?
> > If that works we can add the PIPEDMC_ERROR from PTL onwards.
> > Then here we can change code to create a mask and then return it finally like
> :
> >
> > mask = PIPEDMC_FLIPQ_PROG_DONE
> >
> > if display ver >= 30
> > mask |= PIPEDMC_ERROR
> >
> > if display ver < 35
> > mask |= PIPEDMC_GTT_FAULT |
> > PIPEDMC_ATS_FAULT;
> >
> > Return mask;
> >
> > Obviously that is if PIPEDMC_ERROR works on PTL properly.
>
> Thank you for spotting this, I think its better to add above logic in new series
> rather than combing with 35+ bit mask update.
>
> Regards,
> Dibin

If that is the case then I think its better to drop this patch altogether.
We have a justification of why we remove bits in first patch, that was a change in NVL H/w.
But this change was introduced in LNL.
Without a strong reasoning of why you are enabling this is in NVL and not in PTL (which I don’t see in this patch series)
I suggest you add this patch with as a part of the series where you have a use case for it. And if there too you only add it for NVL
You will need to add a comments as to why this is not enabled for PTL.

Regards,
Suraj Kandpal

>
> >
> > Regards,
> > Suraj Kandpal
> >
> >> /*
> >> * FIXME PIPEDMC_ERROR not enabled for now due to LNL pipe B
> >> --
> >> 2.43.0