[PATCH] drm: avoid switching to text console if there is no panic timeout

[Stéphane Marchesin]

On Mon, Oct 17, 2011 at 17:06, Mandeep Singh Baines <msb at chromium.org> wrote:
> From: Hugh Dickins <hughd at chromium.org>
>
> Add a check for panic_timeout in the drm_fb_helper_panic() notifier: if
> we're going to reboot immediately, the user will not be able to see the
> messages anyway, and messing with the video mode may display artifacts,
> and certainly get into several layers of complexity (including mutexes and
> memory allocations) which we shall be much safer to avoid.
>
> Signed-off-by: Hugh Dickins <hughd at google.com>
> [ Edited commit message and modified to short-circuit panic_timeout < 0
>  instead of testing panic_timeout >= 0.  -Mandeep ]
> Signed-off-by: Mandeep Singh Baines <msb at chromium.org>

Acked-by: Stéphane Marchesin <marcheu at chromium.org>

> Cc: Dave Airlie <airlied at redhat.com>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: dri-devel at lists.freedesktop.org
> ---
>  drivers/gpu/drm/drm_fb_helper.c |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index f7c6854..0e62c93 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -254,6 +254,13 @@ bool drm_fb_helper_force_kernel_mode(void)
>  int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
>                        void *panic_str)
>  {
> +       /*
> +        * It's a waste of time and effort to switch back to text console
> +        * if the kernel should reboot before panic messages can be seen.
> +        */
> +       if (panic_timeout < 0)
> +               return 0;
> +
>        printk(KERN_ERR "panic occurred, switching back to text console\n");
>        return drm_fb_helper_force_kernel_mode();
>  }
> --
> 1.7.3.1
>
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