Re: [PATCH 1/2] Revert "drm/amd: Remove freesync video mode amdgpu parameter"

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 28.02.24 um 15:23 schrieb Alex Deucher:
> On Wed, Feb 28, 2024 at 2:03 AM Christian König
> <ckoenig.leichtzumerken@gmail.com> wrote:
>> Am 27.02.24 um 19:48 schrieb Alex Deucher:
>>> This reverts commit e94e787e37b99645e7c02d20d0a1ba0f8a18a82a.
>>>
>>> This conflicts with how compositors want to handle VRR.  Now
>>> that compositors actually handle VRR, we probably don't need
>>> freesync video.
>>>
>>> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2985
>> Scratching my head what actually happens here? Doesn't the problem then
>> just depend on a module parameter?
> Yes.  The problem is that when freesync video is enabled, compositors
> don't know which modes are actual modes and which are a VRR video
> mode.  There are still customers that want the vrr video mode smooth
> video playback, but compositors don't want this by default.  I guess
> the alternative is to just drop this feature altogether now that
> compositors and media players are starting to support this properly.

That's what I would suggest as well.

As far as I can see adding those modes is actually buggy behavior and we 
need to avoid it.

Christian.

>
> Alex
>
>> Regards,
>> Christian.
>>
>>> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu.h     |  1 +
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 27 +++++++++++++++++++++++++
>>>    2 files changed, 28 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 0e365cadcc3fc..925026c183f41 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -194,6 +194,7 @@ extern int amdgpu_emu_mode;
>>>    extern uint amdgpu_smu_memory_pool_size;
>>>    extern int amdgpu_smu_pptable_id;
>>>    extern uint amdgpu_dc_feature_mask;
>>> +extern uint amdgpu_freesync_vid_mode;
>>>    extern uint amdgpu_dc_debug_mask;
>>>    extern uint amdgpu_dc_visual_confirm;
>>>    extern int amdgpu_dm_abm_level;
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> index 15a8a64fc4e28..82b154b103f43 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> @@ -199,6 +199,7 @@ int amdgpu_mes_kiq;
>>>    int amdgpu_noretry = -1;
>>>    int amdgpu_force_asic_type = -1;
>>>    int amdgpu_tmz = -1; /* auto */
>>> +uint amdgpu_freesync_vid_mode;
>>>    int amdgpu_reset_method = -1; /* auto */
>>>    int amdgpu_num_kcq = -1;
>>>    int amdgpu_smartshift_bias;
>>> @@ -883,6 +884,32 @@ module_param_named(damageclips, amdgpu_damage_clips, int, 0444);
>>>    MODULE_PARM_DESC(tmz, "Enable TMZ feature (-1 = auto (default), 0 = off, 1 = on)");
>>>    module_param_named(tmz, amdgpu_tmz, int, 0444);
>>>
>>> +/**
>>> + * DOC: freesync_video (uint)
>>> + * Enable the optimization to adjust front porch timing to achieve seamless
>>> + * mode change experience when setting a freesync supported mode for which full
>>> + * modeset is not needed.
>>> + *
>>> + * The Display Core will add a set of modes derived from the base FreeSync
>>> + * video mode into the corresponding connector's mode list based on commonly
>>> + * used refresh rates and VRR range of the connected display, when users enable
>>> + * this feature. From the userspace perspective, they can see a seamless mode
>>> + * change experience when the change between different refresh rates under the
>>> + * same resolution. Additionally, userspace applications such as Video playback
>>> + * can read this modeset list and change the refresh rate based on the video
>>> + * frame rate. Finally, the userspace can also derive an appropriate mode for a
>>> + * particular refresh rate based on the FreeSync Mode and add it to the
>>> + * connector's mode list.
>>> + *
>>> + * Note: This is an experimental feature.
>>> + *
>>> + * The default value: 0 (off).
>>> + */
>>> +MODULE_PARM_DESC(
>>> +     freesync_video,
>>> +     "Enable freesync modesetting optimization feature (0 = off (default), 1 = on)");
>>> +module_param_named(freesync_video, amdgpu_freesync_vid_mode, uint, 0444);
>>> +
>>>    /**
>>>     * DOC: reset_method (int)
>>>     * GPU reset method (-1 = auto (default), 0 = legacy, 1 = mode0, 2 = mode1, 3 = mode2, 4 = baco)