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    SubjectRe: [PATCH] drm: avoid switching to text console if there is no panic timeout
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    On Tue, Oct 18, 2011 at 10:19 AM, Dave Young <hidave.darkstar@gmail.com> wrote:
    > On Tue, Oct 18, 2011 at 8:06 AM, Mandeep Singh Baines <msb@chromium.org> wrote:
    >> From: Hugh Dickins <hughd@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.
    >
    > There's one exception is use printk_delay

    OTOH the complexity do exist also when timeout is set, IMHO it is worth

    >
    >>
    >> Signed-off-by: Hugh Dickins <hughd@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@chromium.org>
    >> Cc: Dave Airlie <airlied@redhat.com>
    >> Cc: Andrew Morton <akpm@linux-foundation.org>
    >> Cc: dri-devel@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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    >
    >
    >
    > --
    > Regards
    > Dave
    >



    --
    Regards
    Dave
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