On Thu, Jul 03, 2025 at 04:14:51PM +0300, Luca Coelho wrote:
> On Thu, 2025-06-26 at 11:20 +0300, Imre Deak wrote:
> > From: Imre Deak <imre.d...@gmail.com>
> >
> > Only those IRQs should be acked that are handled, however for SST all
> > IRQs triggered by the sink are acked. This can be a problem for flags
> > that are reserved/reading zero at a given moment, but become used for
> > some purpose - with a side-effect if set - in a future DPCD revision.
> >
> > Fix the above by acking only those device service IRQs that will be
> > handled. While at it add asserts that only the known/acked device
> > service IRQs are handled both in the MST and SST case.
> >
> > Signed-off-by: Imre Deak <imre.d...@gmail.com>
> > ---
> > drivers/gpu/drm/i915/display/intel_dp.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 52249fa5c8a6d..6f67fac9724e1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -4537,6 +4537,14 @@ intel_dp_mst_disconnect(struct intel_dp *intel_dp)
> > drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst.mgr, intel_dp->is_mst);
> > }
> >
> > +#define INTEL_DP_DEVICE_SERVICE_IRQ_MASK_SST
> > (DP_AUTOMATED_TEST_REQUEST | \
> > + DP_CP_IRQ | \
> > + DP_SINK_SPECIFIC_IRQ)
> > +
> > +#define INTEL_DP_DEVICE_SERVICE_IRQ_MASK_MST (DP_CP_IRQ | \
> > + DP_DOWN_REP_MSG_RDY | \
> > + DP_UP_REQ_MSG_RDY)
> > +
> > static bool
> > intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *esi)
> > {
> > @@ -4628,6 +4636,8 @@ static bool
> > intel_dp_get_and_ack_sink_irq_esi_sst(struct intel_dp *intel_dp, u8
> > encoder->base.base.id, encoder->base.name,
> > esi);
> >
> > + esi[1] &= INTEL_DP_DEVICE_SERVICE_IRQ_MASK_SST;
> > +
> > if (mem_is_zero(&esi[1], 3))
> > return true;
> >
> > @@ -5172,6 +5182,8 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
> > if (mem_is_zero(ack, sizeof(ack)))
> > break;
> >
> > + drm_WARN_ON(display->drm, ack[1] &
> > ~INTEL_DP_DEVICE_SERVICE_IRQ_MASK_MST);
> > +
> > if (!intel_dp_ack_sink_irq_esi(intel_dp, ack))
> > drm_dbg_kms(display->drm, "Failed to ack ESI\n");
> >
> > @@ -5456,6 +5468,8 @@ static void intel_dp_handle_device_service_irq(struct
> > intel_dp *intel_dp, u8 irq
> > {
> > struct intel_display *display = to_intel_display(intel_dp);
> >
> > + drm_WARN_ON(display->drm, irq_mask &
> > ~INTEL_DP_DEVICE_SERVICE_IRQ_MASK_SST);
> > +
> > if (irq_mask & DP_AUTOMATED_TEST_REQUEST)
> > intel_dp_test_request(intel_dp);
> >
>
> Evidently, this function is specific to SST irq. Wouldn't it be better
> to have _sst in the name like in "intel_dp_check_mst_status()"? This
> function is probably in an earlier patch, though, so if handled it
> should be obviously be done there.
Yes, it used to be SST specific, but patch 18 reused it for MST as well.
> Otherwise:
>
> Reviewed-by: Luca Coelho <luciano.coe...@intel.com>
>
> --
> Cheers,
> Luca.
