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

[Jani Nikula]

On Thu, 17 Mar 2016, "Sharma, Shashank" <shashank.sharma at intel.com> wrote:
> [ text/plain ]
> Hey Chris,
> I added comments for both Ville and you, please help me to understand this.
>
> Regards
> Shashank
>
> On 3/17/2016 9:51 PM, Ville Syrjälä wrote:
>> On Thu, Mar 17, 2016 at 09:35:30PM +0530, Sharma, Shashank wrote:
>>> Regards
>>> Shashank
>>>
>>> On 3/17/2016 9:31 PM, Ville Syrjälä wrote:
>>>> On Thu, Mar 17, 2016 at 09:15:39PM +0530, Sharma, Shashank wrote:
>>>>> Regards
>>>>> Shashank
>>>>>
>>>>> On 3/17/2016 6:34 PM, Ville Syrjälä wrote:
>>>>>> On Thu, Mar 17, 2016 at 01:29:25PM +0530, Shashank Sharma wrote:
>>>>>>> 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
>>>>>>>
>>>>>>> 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;
>>>>>>> +	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)) {
>>>>>>> +		for (try = 0; !live_status && try < 9; try++) {
>>>>>>> +			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");
>>>>>>>     	}
>>>>>>>
>>>>>>> -	if (!live_status)
>>>>>>> -		DRM_DEBUG_KMS("Live status not up!");
>>>>>>> -
>>>>>>
>>>>>> As I said before, I think this whole thing could be solved with a simple
>>>>>> two-liner here:
>>>>>>
>>>>>> +	if (...)
>>>>>> +		live_status = true;
>>>>>>
>>>>> Yes I remember, and I replied on that already that why we would like to
>>>>> keep the live status check. In fact I would be ok to remove this check
>>>>> if you can suggest some other way of making this work for other
>>>>> operating systems/sw platforms.
>>>>
>>>> My two liner would keep the check.
>>>>
>>> Sorry, I might have not understood you properly.
>>> Do you mean:
>>> 	if (INTEL_INFO(dev)->gen < 7 && IS_IVYBRIDGE(dev)) {
>>> 		live_status = true;
>>> 	} else {
>>> 		do the same looping for retry;
>>> 	}
>>
>> No, I mean
>>
>> {
>> 	...
>> 	do loop;
>>
>> 	if (!live_status)
>> 		DRM_DEBUG_KMS("Live status not up!");
>>
>> +	if (don't trust live status)
>> +		live_status = true;
>> 	
>> 	intel_hdmi_unset_edid();
>> 	
>> 	if (intel_hdmi_set_edid(live_status)) {
>> 	...
>> }
>>
>>
> In fact, this is what I have done.
> If you see the change in this patch,

Actually, not. You set live_status to true in the beginning, and your
loop condition has !live_status, i.e. you won't check live status even
once on any platform. Which is what I said in my review.

BR,
Jani.


> 	/* Lets make live status true for < VLV platforms */
> 	bool live_status = true;
>
> 	blah....
> 	blah....
>
> 	/* Check live status only for newer platforms */
> 	if (this is VLV or later platforms) {
> 		live_status = read_real_live_status();
> 	}
> 	intel_hdmi_unset_edid();
> 	intel_hdmi_set_edid(live_status);
>
> Now, my question is, do you want to remove live_status check for VLV and 
> other platforms too ? or this is good enough ?
> 	
>>>
>>>>>>>     	intel_hdmi_unset_edid(connector);
>>>>>>>
>>>>>>>     	if (intel_hdmi_set_edid(connector, live_status)) {
>>>>>>> --
>>>>>>> 1.9.1
>>>>>>
>>>>
>>

-- 
Jani Nikula, Intel Open Source Technology Center