[PATCH 05/18] fbdev: initialize yoffset of varinfo

[Marc Chalain]

2013/6/21 David Herrmann <dh.herrmann at gmail.com>

> Hi
>
> On Fri, Jun 21, 2013 at 10:49 AM, mchalain [marc.chalain at gmail.com]
> <marc.chalain at gmail.com> wrote:
> > From: mchalain <marc.chalain at gmail.com>
> >
> >  it initializes varinfo.yoffset. varinfo.yoffset has to
> >  point on the beginning of the video memory.
> >  The card uses this value to push on the screen a part of
> >  the video memory when this one is larger than the screen.
> >
> > ---
> >  weston/src/compositor-fbdev.c |    6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/weston/src/compositor-fbdev.c
> b/weston/src/compositor-fbdev.c
> > index adfb67a..d2aee9b 100644
> > --- a/weston/src/compositor-fbdev.c
> > +++ b/weston/src/compositor-fbdev.c
> > @@ -368,6 +368,11 @@ fbdev_query_screen_info(struct fbdev_output
> *output, int fd,
> >                 return -1;
> >         }
> >
> > +       if (varinfo.yoffset != 0) {
> > +               varinfo.yoffset = 0;
> > +               if (ioctl(fd, FBIOPAN_DISPLAY, &varinfo) < 0)
> > +                       return -1;
> > +       }
>
> Why do you need this? It's unnecessary. We call FBIOPUT_VSCREENINFO
> after fbdev_query_screen_info(), anyway. Furthermore, not all drivers
> support panning even though the yoffset may be non-zero (you need
> FBIOPUT_VSCREENINFO then).
>
> I think you can just drop this here but keep the yoffset=0 below.
>
>
where do you use  FBIOPUT_VSCREENINFO ? I only find inside
fbdev_set_screen_info but this function is called only when the output is
reenable not at the startup.
It seems strange that FBIOPAN_DISPLAY is not supported by some devices. I
used this one to not set all the varinfo on the device and to be faster.
If yoffset may be non-zero this backend shouldn't work this kind of devices
and we have to change the painting functions.

>         return 1;
> >  }
> >
> > @@ -404,6 +409,7 @@ fbdev_set_screen_info(struct fbdev_output *output,
> int fd,
> >         varinfo.blue.length = 8;
> >         varinfo.blue.msb_right = 0;
> >
> > +       varinfo.yoffset = 0;
>
> Yep, this is definitely needed.
>
> Regards
> David
>
> >         /* Set the device's screen information. */
> >         if (ioctl(fd, FBIOPUT_VSCREENINFO, &varinfo) < 0) {
> >                 return -1;
> > --
> > 1.7.9.5
> >
> > _______________________________________________
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> > wayland-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/wayland-devel
>
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