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

[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@xxxxxxx>
> > Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx # 6.1+
> > Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2519
> > Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
> > ---
> > 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?

> 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