Re: [PATCH 11/20] drm/i915/dp: Reprobe connector if getting/acking device IRQs fails

[Imre Deak <imre.deak@intel.com>]

On Thu, Jun 26, 2025 at 12:12:11PM +0300, Jani Nikula wrote:
> On Thu, 26 Jun 2025, Imre Deak <imre.deak@intel.com> wrote:
> > From: Imre Deak <imre.deak@gmail.com>
> >
> > An AUX access failure during HPD IRQ handling should be handled by
> > falling back to a full connector detection, ensure that if the failure
> > happens while reading/acking a device service IRQ.
> >
> > Signed-off-by: Imre Deak <imre.deak@gmail.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp.c | 21 +++++++++++++++------
> >  1 file changed, 15 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 7793a72983abd..7eb208d2c321b 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -5393,16 +5393,20 @@ void intel_dp_check_link_state(struct intel_dp *intel_dp)
> >  	intel_encoder_link_check_queue_work(encoder, 0);
> >  }
> >  
> > -static void intel_dp_check_device_service_irq(struct intel_dp *intel_dp)
> > +static bool intel_dp_check_device_service_irq(struct intel_dp *intel_dp)
> 
> I don't think "check" is very intuitive in function names. Check
> something, but then what? Is it like an assert or does it do something
> active or what?
> 
> What does a boolean return from a check function mean?
> 
> It's not obvious to the reader at all.

I agree, but in this patch I didn't want to change the function name.

> 
> >  {
> >  	struct intel_display *display = to_intel_display(intel_dp);
> >  	u8 val;
> >  
> >  	if (drm_dp_dpcd_readb(&intel_dp->aux,
> > -			      DP_DEVICE_SERVICE_IRQ_VECTOR, &val) != 1 || !val)
> > -		return;
> > +			      DP_DEVICE_SERVICE_IRQ_VECTOR, &val) != 1)
> > +		return true;
> 
> Looks like true means the check failed... while usually true for boolean
> functions means success.

The function returns true as before if a full connector detection is needed.

> 
> >  
> > -	drm_dp_dpcd_writeb(&intel_dp->aux, DP_DEVICE_SERVICE_IRQ_VECTOR, val);
> > +	if (!val)
> > +		return false;
> > +
> > +	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_DEVICE_SERVICE_IRQ_VECTOR, val) != 1)
> > +		return true;
> >  
> >  	if (val & DP_AUTOMATED_TEST_REQUEST)
> >  		intel_dp_test_request(intel_dp);
> 
> Whoa, it's not a *check* function at all?! It actually *handles* the
> service irqs.
> 
> Can we rephrase the function name?

I want to keep the function name in this patch. In the following patches
I will separate this part and rename it to
intel_dp_get_and_ack_device_service_irq(). 


> int intel_dp_handle_device_service_irq() and int returns maybe?
> BR,
> Jani.
> 
> > @@ -5412,6 +5416,8 @@ static void intel_dp_check_device_service_irq(struct intel_dp *intel_dp)
> >  
> >  	if (val & DP_SINK_SPECIFIC_IRQ)
> >  		drm_dbg_kms(display->drm, "Sink specific irq unhandled\n");
> > +
> > +	return false;
> >  }
> >  
> >  static bool intel_dp_check_link_service_irq(struct intel_dp *intel_dp)
> > @@ -5476,8 +5482,11 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
> >  		/* No need to proceed if we are going to do full detect */
> >  		return false;
> >  
> > -	intel_dp_check_device_service_irq(intel_dp);
> > -	reprobe_needed = intel_dp_check_link_service_irq(intel_dp);
> > +	if (intel_dp_check_device_service_irq(intel_dp))
> > +		reprobe_needed = true;
> > +
> > +	if (intel_dp_check_link_service_irq(intel_dp))
> > +		reprobe_needed = true;
> >  
> >  	/* Handle CEC interrupts, if any */
> >  	drm_dp_cec_irq(&intel_dp->aux);
> 
> -- 
> Jani Nikula, Intel