[igt-dev] [RFC i-g-t] LPSP igt test on TGL

[Jani Nikula]

On Tue, 03 Mar 2020, Anshuman Gupta <anshuman.gupta at intel.com> wrote:
> On 2020-02-27 at 14:44:18 +0200, Jani Nikula wrote:
>> On Thu, 27 Feb 2020, Anshuman Gupta <anshuman.gupta at intel.com> wrote:
>> > Above block diagram depicts lpsp on TGL, while earlier development of
>> > lpsp igt test it has been assumed that every non-edp panel is not a
>> > lpsp panel but it is not true on TGL, any HDMI/DP panel connected on
>> > pipe A and connected to PORT_{A,B,C} is lpsp panel, and DSI panel is
>> > also lpsp panel.
>> >
>> > Currently i915_pm_lpsp igt has been categorized in edp-native and non-edp subtest.
>> > non-edp subtest require the fix to validate the lpsp panels.
>> > My solution approach to check the port on which DP/HDMI connector is currently 
>> > connected.
>> > if (port <= PORT_C)
>> >     lpsp_should_be_enabled.
>> > else
>> >     lpsp_should_be_disabled.
>> >  
>> > Currently there are two igt i915_pm_lpsp, i915_pm_rpm require to know
>> > the port of DP/HDMI connector, so we need a igt library function for
>> > that.
>> >
>> > I am looking to parse the i915_display_info to get the port
>> > information, but at same time it seems a fragile solution to me as any
>> > change in i915_display_info will break the test, but i don't have any
>> > other idea to get the port information.
>> >
>> > Please provide your opinion and feedback for the above solution approach.
>> 
>> I'd add a connector specific debugfs file that tells you whether LPSS
>> (Low Power Single Pipe, for those who want to know what the acronym
>> means) is possible and whether it's enabled. Alternatively add the info
>> about LPSS to i915_display_info. But AFAICT there's no need for
>> userspace to know about the port. This also avoids reading the
>> HSW_PWR_WELL_CTL2 register directly.
> Thanks Jani and Ville for your feedback and suggestion, based upon your feedback
> i have following solution approach.
> Add a connector specific debugfs attributes i915_lpsp_cpable.
> for ecah connector if it is lpsp capable, do modeset with pipe A crtc 
> on that connector and validate if power wells above  pg2 are turned off
> by using i915_power_domain_info. 

Why not add a debugfs file that will tell you both, instead of forcing
the userspace to know about the connection between lpsp and pg2?

BR,
Jani.



>
> Thanks ,
> Anshuman
>> 
>> BR,
>> Jani.
>> 
>> 
>> -- 
>> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center