Re: [Intel-gfx] [PATCH] drm/i915/fbdev: Implement fb_dirty for intel custom fb helper

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Dec 21, 2022 at 11:49:59AM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 29.11.22 um 13:43 schrieb Jouni Högander:
> > After splitting generic drm_fb_helper into it's own file it's left to
> > helper implementation to have fb_dirty function. Currently intel
> > fb doesn't have it. This is causing problems when PSR is enabled.
> > 
> > Implement simple fb_dirty callback to deliver notifications to psr
> > about updates in fb console.
> 
> I'm a bit confused about i915's use of fb_dirty here. How is this 
> supposed to interact with mmap?  i915 doesn't use deferred I/O so fbdev 
> mmap will never call fb_dirty if userspace writes to mmap'ed pages. Is 
> this only required for the kernel's graphics console?

It's required for everything. mmap is presumably borked for
the cases where we can't use any hw based damage tracking.

> 
> Best regards
> Thomas
> 
> > 
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Jani Nikula <jani.nikula@intel.com>
> > Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> > ---
> >   drivers/gpu/drm/i915/display/intel_fbdev.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c
> > index 5575d7abdc09..7c7fba3fe69e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
> > @@ -328,8 +328,17 @@ static int intelfb_create(struct drm_fb_helper *helper,
> >   	return ret;
> >   }
> >   
> > +static int intelfb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect *clip)
> > +{
> > +	if (helper->fb->funcs->dirty)
> > +		return helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
> > +
> > +	return 0;
> > +}
> > +
> >   static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
> >   	.fb_probe = intelfb_create,
> > +	.fb_dirty = intelfb_dirty,
> >   };
> >   
> >   static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev




-- 
Ville Syrjälä
Intel