lkml.org 
[lkml]   [2019]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] drm/atmel-hlcdc: prevent divide by zero
On Wed, 9 Jan 2019 11:37:19 +0000
Peter Rosin <peda@axentia.se> wrote:

> On 2019-01-09 11:12, Daniel Vetter wrote:
> > On Tue, Jan 08, 2019 at 12:31:36PM +0000, Peter Rosin wrote:
> >> While trying to temporarily hide a plane, one thing that was attempted
> >> was to call (from libdrm)
> >>
> >> drmModeSetPlane(fd, plane_id, crtc_id, fb_id, 0,
> >> 0, 0, 0, 0, 0, 0, 0, 0);
> >>
> >> This call causes a pair of "Division by zero in kernel." messages. Kill
> >> those messages, but preserve the current behaviour that also happen to
> >> make the plane disappear with the above call.
> >>
> >> Signed-off-by: Peter Rosin <peda@axentia.se>
> >> ---
> >> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 14 ++++++++++----
> >> 1 file changed, 10 insertions(+), 4 deletions(-)
> >>
> >> Side note, when comparing with drm_atomic_helper_check_plane_state(), I get
> >> the feeling that the src rect should be clipped together with the crtc rect
> >> if/when clipping is needed. That function calls drm_rect_clip_scaled(), and
> >> the equivalent does not seem to happen here. Should clipping be performed
> >> on the src rect?
> >
> > Any reasons atmel can't switch over to that helper? Would compute a nice
> > ->visible state variable for you ...
> > -Daniel
>
> I have not researched that, and as stated above, I was not sure if that was the
> correct approach to begin with. Boris, any insights?

You can look at vc4_plane.c if you want an example of how this helper
can be used to get clipped dimensions of the plane.

> Does this code predate the
> helper or something?

Yes, and I must admit I'm not actively maintaining the driver, so there
are probably a few other things we could simplify by using generic
helpers.

>
> Maybe there's some register bit that hides a plane explicitly, matching the
> ->visible state variable? I haven't looked at that either...

I don't think so, but you can simply disable the plane when ->visible
is false.

\
 
 \ /
  Last update: 2019-01-09 13:00    [W:0.556 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site