[PATCH v2] drm/amdgpu: register a dirty framebuffer callback for fbcon

[Hamza Mahfooz]

On 8/23/23 16:51, Alex Deucher wrote:
> @Mahfooz, Hamza
>   can you respin with the NULL check?

sure.

> 
> Alex
> 
> On Wed, Aug 16, 2023 at 10:25 AM Christian König
> <christian.koenig at amd.com> wrote:
>>
>> Am 16.08.23 um 15:41 schrieb Hamza Mahfooz:
>>>
>>> On 8/16/23 01:55, Christian König wrote:
>>>>
>>>>
>>>> Am 15.08.23 um 19:26 schrieb Hamza Mahfooz:
>>>>> fbcon requires that we implement &drm_framebuffer_funcs.dirty.
>>>>> Otherwise, the framebuffer might take a while to flush (which would
>>>>> manifest as noticeable lag). However, we can't enable this callback for
>>>>> non-fbcon cases since it might cause too many atomic commits to be made
>>>>> at once. So, implement amdgpu_dirtyfb() and only enable it for fbcon
>>>>> framebuffers on devices that support atomic KMS.
>>>>>
>>>>> Cc: Aurabindo Pillai <aurabindo.pillai at amd.com>
>>>>> Cc: Mario Limonciello <mario.limonciello at amd.com>
>>>>> Cc: stable at vger.kernel.org # 6.1+
>>>>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2519
>>>>> Signed-off-by: Hamza Mahfooz <hamza.mahfooz at amd.com>
>>>>> ---
>>>>> v2: update variable names
>>>>> ---
>>>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 26
>>>>> ++++++++++++++++++++-
>>>>>    1 file changed, 25 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>>>> index d20dd3f852fc..d3b59f99cb7c 100644
>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
>>>>> @@ -38,6 +38,8 @@
>>>>>    #include <linux/pci.h>
>>>>>    #include <linux/pm_runtime.h>
>>>>>    #include <drm/drm_crtc_helper.h>
>>>>> +#include <drm/drm_damage_helper.h>
>>>>> +#include <drm/drm_drv.h>
>>>>>    #include <drm/drm_edid.h>
>>>>>    #include <drm/drm_fb_helper.h>
>>>>>    #include <drm/drm_gem_framebuffer_helper.h>
>>>>> @@ -532,11 +534,29 @@ bool amdgpu_display_ddc_probe(struct
>>>>> amdgpu_connector *amdgpu_connector,
>>>>>        return true;
>>>>>    }
>>>>> +static int amdgpu_dirtyfb(struct drm_framebuffer *fb, struct
>>>>> drm_file *file,
>>>>> +              unsigned int flags, unsigned int color,
>>>>> +              struct drm_clip_rect *clips, unsigned int num_clips)
>>>>> +{
>>>>> +
>>>>> +    if (strcmp(fb->comm, "[fbcon]"))
>>>>> +        return -ENOSYS;
>>>>
>>>> Once more to the v2 of this patch: Tests like those are a pretty big
>>>> NO-GO for upstreaming.
>>>
>>> On closer inspection it is actually sufficient to check if `file` is
>>> NULL here (since it means that the request isn't from userspace). So, do
>>> you think that would be palatable for upstream?
>>
>> That's certainly better than doing a string compare, but I'm not sure if
>> that's sufficient.
>>
>> In general drivers shouldn't have any special handling for fdcon.
>>
>> You should probably have Thomas Zimmermann <tzimmermann at suse.de> take a
>> look at this.
>>
>> Regards,
>> Christian.
>>
>>>
>>>>
>>>> Regards,
>>>> Christian.
>>>>
>>>>> +
>>>>> +    return drm_atomic_helper_dirtyfb(fb, file, flags, color, clips,
>>>>> +                     num_clips);
>>>>> +}
>>>>> +
>>>>>    static const struct drm_framebuffer_funcs amdgpu_fb_funcs = {
>>>>>        .destroy = drm_gem_fb_destroy,
>>>>>        .create_handle = drm_gem_fb_create_handle,
>>>>>    };
>>>>> +static const struct drm_framebuffer_funcs amdgpu_fb_funcs_atomic = {
>>>>> +    .destroy = drm_gem_fb_destroy,
>>>>> +    .create_handle = drm_gem_fb_create_handle,
>>>>> +    .dirty = amdgpu_dirtyfb
>>>>> +};
>>>>> +
>>>>>    uint32_t amdgpu_display_supported_domains(struct amdgpu_device *adev,
>>>>>                          uint64_t bo_flags)
>>>>>    {
>>>>> @@ -1139,7 +1159,11 @@ static int
>>>>> amdgpu_display_gem_fb_verify_and_init(struct drm_device *dev,
>>>>>        if (ret)
>>>>>            goto err;
>>>>> -    ret = drm_framebuffer_init(dev, &rfb->base, &amdgpu_fb_funcs);
>>>>> +    if (drm_drv_uses_atomic_modeset(dev))
>>>>> +        ret = drm_framebuffer_init(dev, &rfb->base,
>>>>> +                       &amdgpu_fb_funcs_atomic);
>>>>> +    else
>>>>> +        ret = drm_framebuffer_init(dev, &rfb->base, &amdgpu_fb_funcs);
>>>>>        if (ret)
>>>>>            goto err;
>>>>
>>
-- 
Hamza