linux-kernel - Re: [PATCH] fb: udl: fix build without CONFIG_FB_DEFERRED

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Date:   Wed, 24 Aug 2016 11:01:17 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Dave Airlie <airlied@...hat.com>, David Airlie <airlied@...ux.ie>,
        Noralf Trønnes <noralf@...nnes.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fb: udl: fix build without CONFIG_FB_DEFERRED_IO

On Wed, Aug 24, 2016 at 10:27 AM, Arnd Bergmann <arnd@...db.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@...db.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.
-Daniel

> ---
>  drivers/gpu/drm/udl/udl_fb.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
> index d5df555aeba0..fec47733e57e 100644
> --- a/drivers/gpu/drm/udl/udl_fb.c
> +++ b/drivers/gpu/drm/udl/udl_fb.c
> @@ -24,11 +24,14 @@
>
>  #define DL_DEFIO_WRITE_DELAY    (HZ/20) /* fb_deferred_io.delay in jiffies */
>
> -static int fb_defio = 0;  /* Optionally enable experimental fb_defio mmap support */
>  static int fb_bpp = 16;
>
>  module_param(fb_bpp, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
> +
> +#ifdef CONFIG_FB_DEFERRED_IO
> +static int fb_defio = 0;  /* Optionally enable experimental fb_defio mmap support */
>  module_param(fb_defio, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
> +#endif
>
>  struct udl_fbdev {
>         struct drm_fb_helper helper;
> @@ -203,6 +206,7 @@ static int udl_fb_open(struct fb_info *info, int user)
>
>         ufbdev->fb_count++;
>
> +#ifdef CONFIG_FB_DEFERRED_IO
>         if (fb_defio && (info->fbdefio == NULL)) {
>                 /* enable defio at last moment if not disabled by client */
>
> @@ -218,6 +222,7 @@ static int udl_fb_open(struct fb_info *info, int user)
>                 info->fbdefio = fbdefio;
>                 fb_deferred_io_init(info);
>         }
> +#endif
>
>         pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
>                   info->node, user, info, ufbdev->fb_count);
> @@ -235,12 +240,14 @@ static int udl_fb_release(struct fb_info *info, int user)
>
>         ufbdev->fb_count--;
>
> +#ifdef CONFIG_FB_DEFERRED_IO
>         if ((ufbdev->fb_count == 0) && (info->fbdefio)) {
>                 fb_deferred_io_cleanup(info);
>                 kfree(info->fbdefio);
>                 info->fbdefio = NULL;
>                 info->fbops->fb_mmap = udl_fb_mmap;
>         }
> +#endif
>
>         pr_warn("released /dev/fb%d user=%d count=%d\n",
>                 info->node, user, ufbdev->fb_count);
> --
> 2.9.0
>



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch