[Intel-gfx] [PATCH 2/2] drm/i915/dp: use opregion mailbox #5 EDID for eDP, if available

[Lee, Shawn C]

On Mon, Oct 12, 2020 at 5:09 PM, Jani Nikula wrote:
>On Mon, 12 Oct 2020, "Lee, Shawn C" <shawn.c.lee at intel.com> wrote:
>> On Fri, Aug 28, 2020 at 06:19AM, Shankar Uma wrote:
>>>> -----Original Message-----
>>>> From: Jani Nikula <jani.nikula at intel.com>
>>>> Sent: Friday, August 28, 2020 11:50 AM
>>>> To: intel-gfx at lists.freedesktop.org
>>>> Cc: Nikula, Jani <jani.nikula at intel.com>; Shankar, Uma 
>>>> <uma.shankar at intel.com>
>>>> Subject: [PATCH 2/2] drm/i915/dp: use opregion mailbox #5 EDID for 
>>>> eDP, if available
>>>>
>>>> If a panel's EDID is broken, there may be an override EDID set in 
>>>> the ACPI OpRegion mailbox #5. Use it if available.
>>>
>>>Looks Good to me.
>>>Reviewed-by: Uma Shankar <uma.shankar at intel.com>
>>>
>>>> Cc: Uma Shankar <uma.shankar at intel.com>
>>>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>>>> ---
>>>>  drivers/gpu/drm/i915/display/intel_dp.c | 3 +++
>>>>  1 file changed, 3 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
>>>> b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> index c57ac83bf563..d1307be196a2 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> @@ -8114,6 +8114,9 @@ static bool intel_edp_init_connector(struct 
>>>> intel_dp *intel_dp,  goto out_vdd_off;  }
>>>>
>>>> +/* Set up override EDID, if any, from ACPI OpRegion */ 
>>>> +intel_opregion_edid_override(intel_connector);
>>>> +
>>
>> Customer report DUT still get EDID from eDP panel instead of mailbox #5.
>> After some investigations, this change can retrieve EDID from mailbox #5 properly.
>> But driver still used panel's EDID to enable eDP display. This is 
>> because of drm_get_edid() was executed after 
>> intel_opregion_edid_override(). drm_get_edid() return panel's EDID and overwrite mailbox #5's.
>
>In recent kernels, drm_get_edid() respects EDID override, and calling
>drm_get_edid() will return the override EDID from mailbox #5 instead of retrieving the actual EDID.
>
>Check the kernel version they're using and the drm_get_edid() implementation.
>
>BR,
>Jani.
>

Just confirm customer is using kernel v5.8. Seems drm_edid.c already include
the change for override_edid.

BTW. override_edid should be "true" and used to over EDID in intel_opregion_edid_override() in patch 1. Right? 
But it is "false" in the patch 1.

+	connector->override_edid = false;

Best regards,
Shawn

>
>>
>> We try to move drm_get_edid() before intel_opregion_edid_override().
>> The test result is positive, mailbox #5 EDID will substitute for panel's.
>> It seems we may need some additional change for this patch. Thanks!
>>
>> Best regards,
>> Shawn
>>
>>>>  mutex_lock(&dev->mode_config.mutex);
>>>>  edid = drm_get_edid(connector, &intel_dp->aux.ddc);  if (edid) {
>>>> --
>>>> 2.20.1
>
>-- 
>Jani Nikula, Intel Open Source Graphics Center
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