On Thu, 26 Jun 2025, Imre Deak <imre.d...@intel.com> wrote:
> On Thu, Jun 26, 2025 at 01:23:12PM +0300, Jani Nikula wrote:
>> On Thu, 26 Jun 2025, Imre Deak <imre.d...@intel.com> wrote:
>> > On Thu, Jun 26, 2025 at 12:12:11PM +0300, Jani Nikula wrote:
>> >> On Thu, 26 Jun 2025, Imre Deak <imre.d...@intel.com> wrote:
>> >> > From: Imre Deak <imre.d...@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.d...@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.
>>
>> Arguably adding a return value changes the meaning already...
>>
>> >
>> >>
>> >> > {
>> >> > 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.
>>
>> But it didn't return anything before! And that meaning is not conveyed
>> to the reader in *any* reasonable way!
>
> This function is the counterpart of intel_dp_check_link_service_irq()
> both functions having the same purpose, reading and handling HPD IRQs.
> The latter one's return value is true if a reprobe is needed and this
> patch doesn't change that, it keeps the two functions behave the same
> way.
>
>> The absolute minimum is to add a comment (mind you, kernel-doc is
>> overkill) stating what the return value means.
>
> The function name will change in a follow-up patch and I think that
> doesn't require a comment on the return value.
>
>> >>
>> >> >
>> >> > - 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().
>>
>> Right, saw that now. But even for that function name the meaning of the
>> return value is ambiguous.
>
> All the get/ack IRQ functions in intel_dp.c return true for success.
Argh. You just said it doesn't mean success/failure, it means if full
connector detection is needed?!
BR,
Jani
>
>>
>> BR,
>> Jani.
>>
>> >
>> >
>> >> 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
>>
>> --
>> Jani Nikula, Intel
--
Jani Nikula, Intel
