Hi On Fri, Jun 21, 2013 at 12:05 PM, Marc Chalain <marc.chal...@gmail.com> wrote: > > > 2013/6/21 David Herrmann <dh.herrm...@gmail.com> >> >> Hi >> >> On Fri, Jun 21, 2013 at 11:43 AM, Marc Chalain <marc.chal...@gmail.com> >> wrote: >> > >> > 2013/6/21 David Herrmann <dh.herrm...@gmail.com> >> >> >> >> Hi >> >> >> >> On Fri, Jun 21, 2013 at 10:49 AM, mchalain [marc.chal...@gmail.com] >> >> <marc.chal...@gmail.com> wrote: >> >> > From: mchalain <marc.chal...@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. >> >> My bad! >> But still, you now call FBIOPAN_DISPLAY on _every_ >> fbdev_query_screen_info() while it is only needed during initial setup >> as VT_ENTER calls fbdev_set_screen_info(), anyway. So instead, I'd >> recommend to just call fbdev_set_screen_info() during initial setup as >> well. >> > > No I call FBIOPAN_DISPLAY only at startup after yoffset is set to 0
You call it everytime yoffset isn't 0. So if you VT_LEAVE, another application changes the yoffset for whatever reason and we VT_ENTER, you will end up calling FBIOPAN_DISPLAY again followed by fbdev_set_screen_info() if the screen-info changed. Don't expect applications on other VTs to behave as expected. They may do anything! They may even use some acceleration which we in weston aren't aware of. >> > 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. >> >> See ./drivers/video/fbmem.c fb_pan_display(). Trivial fbdev drivers >> might not support it, but user-space can still set the offset via >> FBIOPUT_VSCREENINFO. If you want, you can call FBIOPAN_DISPLAY and if >> it fails, you use FBIOPUT_VSCREENINFO. >> > I read the yoffset hasn't to be null in FB_VMODE_YWRAP . But yoffset is > only used for panning. > It's useless to set it if it doesn't use (fbmem.c uses yoffset only for > panning in your example too) A driver may not support FBIOPAN_DISPLAY but still support panning via FBIOPUT_VSCREENINFO. If any framebuffer parameter change requires a full modeset, there is no reason to support FBIOPAN_DISPLAY. But panning may still be supported via yoffset and FBIOPUT_VSCREENINFO. Cheers David _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel