[PATCH] fb: udl: fix build without CONFIG_FB_DEFERRED_IO

[Arnd Bergmann]

On Wednesday, August 24, 2016 11:01:17 AM CEST Daniel Vetter wrote:
> On Wed, Aug 24, 2016 at 10:27 AM, Arnd Bergmann <arnd at arndb.de> wrote:
> > A cleanup in v4.8 dropped several dependencies, but caused the udl driver
> > to fail building when CONFIG_FB_DEFERRED_IO is not set:
> >
> > drivers/gpu/drm/udl/udl_fb.c: In function 'udl_fb_open':
> > drivers/gpu/drm/udl/udl_fb.c:206:23: error: 'struct fb_info' has no member named 'fbdefio'
> >   if (fb_defio && (info->fbdefio == NULL)) {
> >                        ^~
> >
> > This adds an #ifdef check around the code that fails. We know this
> > is safe because it always checks info->fbdefio for being non-NULL,
> > and that member is not defined here.
> >
> > Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> > Fixes: c0f0c177b5a9 ("drm/udl: make fbdev support really optional")
> 
> There's a pile more needed, which is why I just ended up stuffing them
> all into linux-next for 4.9. Is your patch still needed on that? If we
> really want this fixed in 4.8 I guess I can assemble a cherry-pick
> list.

Ok, got it. I think your 0c756134cf76 ("drm: Protect fb_defio in
drivers with CONFIG_KMS_FBDEV_EMULATION") is actually sufficient
for the build break, it's almost the same as my patch anyway.

Alternatively, reverting c0f0c177b5a9 ("drm/udl: make fbdev
support really optional") for v4.8 would work too.

	Arnd