[Intel-gfx] [PATCH] drm/i915: Restrict usage of live status check

[Sharma, Shashank]

Regards
Shashank

On 3/17/2016 2:55 PM, Jani Nikula wrote:
> On Thu, 17 Mar 2016, Shashank Sharma <shashank.sharma at intel.com> wrote:
>> [ text/plain ]
>> This patch restricts usage of live status check for HDMI detection.
>> While testing certain (monitor + cable) combinations with various
>> intel  platforms, it seems that live status register is not reliable
>> on some older devices. So limit the live_status check from VLV onwards.
>>
>> This fixes a regression introduced in:
>> 	commit: 237ed86 "drm/i915: Check live status"
>> 	Author: Sonika Jindal <sonika.jindal at intel.com>
>> 	Date:   Tue Sep 15 09:44:20 2015 +0530
>>
>
> Fixes: 237ed86c693d ("drm/i915: Check live status before reading edid")
> Cc: stable at vger.kernel.org # v4.4
> Bugzilla: ?
>
Let me dig for it ... Do you have a link ? If yes, please share.
>> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_hdmi.c | 22 ++++++++++++++--------
>>   1 file changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
>> index e2dab48..d24d18a 100644
>> --- a/drivers/gpu/drm/i915/intel_hdmi.c
>> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
>> @@ -1397,7 +1397,8 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>>   	enum drm_connector_status status;
>>   	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
>>   	struct drm_i915_private *dev_priv = to_i915(connector->dev);
>> -	bool live_status = false;
>> +	struct drm_device *dev = connector->dev;
>
> This is unnecessary.
>
>> +	bool live_status = true;
>>   	unsigned int try;
>>
>>   	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
>> @@ -1405,16 +1406,21 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>>
>>   	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
>>
>> -	for (try = 0; !live_status && try < 9; try++) {
>> -		if (try)
>> -			msleep(10);
>> -		live_status = intel_digital_port_connected(dev_priv,
>> +	/*
>> +	* Live status check for HDMI detection is not very
>> +	* reliable on older platforms. So insist the live
>> +	* status check for EDID read from VLV onwards.
>> +	*/
>> +	if (INTEL_INFO(dev)->gen >= 7 && !IS_IVYBRIDGE(dev)) {
>
> Replace dev with dev_priv. Both work, it's magic, but we prefer using
> dev_priv where possible.
>
Interesting, will try that out.
> Move try variable declaration here.
>
Got it.
>> +		for (try = 0; !live_status && try < 9; try++) {
>
> You'll now ignore live_status on all platforms. (But please do not turn
> this into a do-while, keep it as a for loop.)
>
>> +			if (try)
>> +				msleep(10);
>> +			live_status = intel_digital_port_connected(dev_priv,
>>   				hdmi_to_dig_port(intel_hdmi));
>> +		}
>> +		DRM_DEBUG_KMS("Live status %s\n", live_status ? "up" : "down");
>
> Consider using onoff(live_status) instead of live_status ? "up" :
> "down".
>
Sounds cool, I dint know about onoff yet, will check.
>>   	}
>>
>> -	if (!live_status)
>> -		DRM_DEBUG_KMS("Live status not up!");
>> -
>>   	intel_hdmi_unset_edid(connector);
>>
>>   	if (intel_hdmi_set_edid(connector, live_status)) {
>