Re: [PATCH 6/6] drm/i915: force full detect on sink count change

[Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>]

On Thursday 14 January 2016 07:20 PM, Ander Conselvan De Oliveira wrote:
> On Tue, 2016-01-05 at 18:20 +0530, Shubhangi Shrivastava wrote:
>> This patch checks for changes in sink count between short pulse
>> hpds and forces full detect when there is a change.
>>
>> This will allow both detection of hotplug and unplug of panels
>> through dongles that give only short pulse for such events.
>>
>> v2: changed variable type from u8 to bool (Jani)
>>      return immediately if perform_full_detect is set(Siva)
>>
>> v3: changed method of determining full detection from using
>>      pointer to return code (Siva)
>>
>> Tested-by: Nathan D Ciobanu <nathan.d.ciobanu@intel.com>
>> Signed-off-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
>> Signed-off-by: Shubhangi Shrivastava <shubhangi.shrivastava@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_dp.c | 30 +++++++++++++++++++++++-------
>>   1 file changed, 23 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>> index 0d58bfd..8a659ee 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -4331,12 +4331,14 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
>>    *  3. Use Link Training from 2.5.3.3 and 3.5.1.3
>>    *  4. Check link status on receipt of hot-plug interrupt
>>    */
>> -static void
>> +static bool
> Please expand the comment above to indicate what the return value of this
> function is supposed to mean.
>
Sure.. Will add..

>>   intel_dp_short_pulse(struct intel_dp *intel_dp)
>>   {
>>   	struct drm_device *dev = intel_dp_to_dev(intel_dp);
>>   	u8 sink_irq_vector;
>>   	u8 link_status[DP_LINK_STATUS_SIZE];
>> +	u8 old_sink_count = intel_dp->sink_count;
>> +	bool ret;
>>   
>>   	/*
>>   	 * Clearing compliance test variables to allow capturing
>> @@ -4348,12 +4350,20 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
>>   
>>   	/* Try to read receiver status if the link appears to be up */
>>   	if (!intel_dp_get_link_status(intel_dp, link_status)) {
>> -		return;
>> +		return false;
>>   	}
>>   
>> -	/* Now read the DPCD to see if it's actually running */
>> -	if (!intel_dp_get_dpcd(intel_dp)) {
>> -		return;
>> +	/*
>> +	 * Now read the DPCD to see if it's actually running
>> +	 * Don't return immediately if dpcd read failed,
>> +	 * if sink count was 1 and dpcd read failed we need
>> +	 * to do full detection
>> +	 */
>> +	ret = intel_dp_get_dpcd(intel_dp);
>> +
>> +	if ((old_sink_count != intel_dp->sink_count) || !ret) {
> I don't see the connection of the comment above with this. If the dpcd read
> fails, the 'return false' will be reached regardless of the previous value of
> intel_dp->sink_count. Did you intend to do something different or did I miss
> something?
>
The code was changed but comment was not updated.. Will change the 
comment to explain correctly.

>> +		/* No need to proceed if we are going to do full detect */
>> +		return false;
>>   	}
>>   
>>   	/* Try to read the source of the interrupt */
>> @@ -4373,6 +4383,8 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
>>   	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>>   	intel_dp_check_link_status(intel_dp);
>>   	drm_modeset_unlock(&dev->mode_config.connection_mutex);
>> +
>> +	return true;
>>   }
>>   
>>   /* XXX this is probably wrong for multiple downstream ports */
>> @@ -5095,8 +5107,12 @@ intel_dp_hpd_pulse(struct intel_digital_port
>> *intel_dig_port, bool long_hpd)
>>   			}
>>   		}
>>   
>> -		if (!intel_dp->is_mst)
>> -			intel_dp_short_pulse(intel_dp);
>> +		if (!intel_dp->is_mst) {
>> +			if (!intel_dp_short_pulse(intel_dp)) {
>> +				intel_dp_long_pulse(intel_dp
>> ->attached_connector);
>> +				goto put_power;
> It could be in a follow up patch, but I think its a good moment to get rid of
> the goto put_power. The only thing they do is skip the 'ret = IRQ_HANDLED'
> assignment now.
>
> Ander
Sure.. Will remove the goto put_power in follow up patch.

>> +			}
>> +		}
>>   	}
>>   
>>   	ret = IRQ_HANDLED;

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