[Intel-gfx] [PATCH v4 3/3] drm/i915/dp: Expose connector VRR info via debugfs

[Michel Dänzer]

On 2020-04-14 2:44 p.m., Daniel Vetter wrote:
> On Mon, Apr 13, 2020 at 10:08:07PM -0700, Manasi Navare wrote:
>> From: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
>>
>> [Why]
>> It's useful to know the min and max vrr range for IGT testing.
>>
>> [How]
>> Expose the min and max vfreq for the connector via a debugfs file
>> on the connector, "i915_vrr_info".
>>
>> Example usage: cat /sys/kernel/debug/dri/0/DP-1/i915_vrr_info
>>
>> v3:
>> * Remove the unnecessary debug print (Manasi)
>> v2:
>> * Fix the typo in max_vfreq (Manasi)
>> * Change the name of node to i915_vrr_info so we can add
>> other vrr info for more debug info (Manasi)
>> * Change the VRR capable to display Yes or No (Manasi)
>> * Fix indentation checkpatch errors (Manasi)
>>
>> Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
>> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Tested-by: Manasi Navare <manasi.d.navare at intel.com>
> 
> So if I'm understanding things correctly AMD butchered the VRR stuff and
> only exposes it when:
> 
> - VRR_ENABLED is set

Not really surprising? :)

> - _and_ you're using the legacy page_flip path, atomic flip doesn't
>   support it

Simon Ser has VRR working with sway using the atomic KMS API.

> - _and_ the PAGE_FLIP_ASYNC flag is set.

AFAIK it works both without and with PAGE_FLIP_ASYNC. (Async just means
tearing if the flip is programmed outside of vertical blank)


-- 
Earthling Michel Dänzer               |               https://redhat.com
Libre software enthusiast             |             Mesa and X developer