Re: [PATCH 3/3] drm/i915: force full detect on sink count change

[Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>]

On 8/26/2015 3:32 PM, Jani Nikula wrote:
> On Tue, 25 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@intel.com> wrote:
>> From: "Thulasimani,Sivakumar" <sivakumar.thulasimani@intel.com>
>>
>> This patch checks for changes in sink count between short pulse
>> hpds and forces full detect when there is a change. This will
>> result in compliance test case 4.2.2.8 passing since it tests
>> for this behavior.
>>
>> This will allow both detection of hotplug and unplug of panels
>> through dongles that give only short pulse for such events.
>>
>> Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dp.c |   20 ++++++++++++++++----
>>   1 file changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> index 834f513..eb3ab41 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -4370,26 +4370,34 @@ go_again:
>>    *  4. Check link status on receipt of hot-plug interrupt
>>    */
>>   static void
>> -intel_dp_check_link_status(struct intel_dp *intel_dp)
>> +intel_dp_check_link_status(struct intel_dp *intel_dp, bool *perform_full_detect)
> You could turn perform_full_detect into a boolean return value which
> this function doesn't have.
sure will do.
>
>>   {
>>   	struct drm_device *dev = intel_dp_to_dev(intel_dp);
>>   	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
>>   	struct intel_crtc *crtc =
>>   		to_intel_crtc(dp_to_dig_port(intel_dp)->base.base.crtc);
>>   	u8 sink_irq_vector;
>> +	u8 old_sink_count = intel_dp->sink_count;
>> +	u8 ret;
> Isn't this a bool, really?
>
>>   	u8 link_status[DP_LINK_STATUS_SIZE];
>>   
>>   	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>>   
>> +	*perform_full_detect = false;
>> +
>>   	/* Try to read receiver status if the link appears to be up */
>>   	if (!intel_dp_get_link_status(intel_dp, link_status)) {
>>   		return;
>>   	}
>>   
>>   	/* Now read the DPCD to see if it's actually running */
>> -	if (!intel_dp_get_dpcd(intel_dp)) {
>> +	ret = intel_dp_get_dpcd(intel_dp);
>> +
>> +	if (old_sink_count != intel_dp->sink_count)
>> +		*perform_full_detect = true;
> Can't trust intel_dp->sink_count without checking the return value. So I
> guess you can call intel_dp_get_dpcd the way it's done now, and move the
> sink count check below it.
>
> BR,
> Jani.

sure will fix this.
>
>> +
>> +	if (!ret)
>>   		return;
>> -	}
>>   
>>   	if (!intel_encoder->base.crtc)
>>   		return;
>> @@ -5031,13 +5039,17 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>>   		}
>>   
>>   		if (!intel_dp->is_mst) {
>> +			bool full_detect;
>>   			/*
>>   			 * we'll check the link status via the normal hot plug path later -
>>   			 * but for short hpds we should check it now
>>   			 */
>>   			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>> -			intel_dp_check_link_status(intel_dp);
>> +			intel_dp_check_link_status(intel_dp, &full_detect);
>>   			drm_modeset_unlock(&dev->mode_config.connection_mutex);
>> +
>> +			if (full_detect)
>> +				goto put_power;
>>   		}
>>   	}
>>   
>> -- 
>> 1.7.9.5
>>

-- 
regards,
Sivakumar

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