[PATCH] drm: fix setting of plane_mask in pan_display_atomic() function for linux-4.4

[chenxb_99091 at 126.com]

From: Xuebing Chen <chenxb_99091 at 126.com>

On Mon, May 25, 2020 at 04:34:28PM +0200, Daniel Vetter wrote:
> On Sat, May 23, 2020 at 11:49:07AM +0800, chenxb_99091 at 126.com wrote:
> > From: Xuebing Chen <chenxb_99091 at 126.com>
> > 
> > The <include/drm/drm_crtc.h> provides drm_for_each_plane_mask macro and
> > plane_mask is defined as bitmask of plane indices, such as
> > 1<<drm_plane_index(plane). This patch fixes error setting of plane_mask
> > in pan_display_atomic() function.
> > 
> > Signed-off-by: Xuebing Chen <chenxb_99091 at 126.com>
> 
> What kernel is this patch against? Latest upstream doesn't have any such
> code anymore ... I'm assuming that Ville fixed this in one of his patches,
> but I can't find the right one just now.

This bug is still present in the longterm-supported versions of kernel 4.4.y, 
including the latest kernel v4.4.224,
See https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/?h=v4.4.224



> -Daniel
> 
> > ---
> >  drivers/gpu/drm/drm_fb_helper.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> > index e449f22..6a9f7ee 100644
> > --- a/drivers/gpu/drm/drm_fb_helper.c
> > +++ b/drivers/gpu/drm/drm_fb_helper.c
> > @@ -1256,7 +1256,7 @@ retry:
> >  			goto fail;
> >  
> >  		plane = mode_set->crtc->primary;
> > -		plane_mask |= drm_plane_index(plane);
> > +		plane_mask |= 1 << drm_plane_index(plane);
> >  		plane->old_fb = plane->fb;
> >  	}
> >  
> > -- 
> > 2.7.4
> > 
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> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch