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

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

[Mandeep Singh Baines]

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.

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

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

[David Rientjes]

On Mon, 17 Oct 2011, Mandeep Singh Baines 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.
> 
> 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

Acked-by: David Rientjes <rientjes@google.com>

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

[David Rientjes]

On Mon, 17 Oct 2011, David Rientjes wrote:

> On Mon, 17 Oct 2011, Mandeep Singh Baines 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.
> > 
> > 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
> 
> Acked-by: David Rientjes <rientjes@google.com>
> 

Dave, where do we stand on this?  I haven't seen it hit Linus' tree and I 
don't see it in git://people.freedesktop.org/~airlied/linux.

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

[Mandeep Singh Baines]

David Rientjes (rientjes@google.com) wrote:
> On Mon, 17 Oct 2011, David Rientjes wrote:
> 
> > On Mon, 17 Oct 2011, Mandeep Singh Baines 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.
> > > 
> > > 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
> > 
> > Acked-by: David Rientjes <rientjes@google.com>
> > 
> 
> Dave, where do we stand on this?  I haven't seen it hit Linus' tree and I 
> don't see it in git://people.freedesktop.org/~airlied/linux.

The last status I have is Andrew pulling it into mmotm on 10/18/11.

Subject: + drm-avoid-switching-to-text-console-if-there-is-no-panic-timeout.patch added to -mm tree
From: akpm@linux-foundation.org
Date: Tue, 18 Oct 2011 15:42:46 -0700


The patch titled
     Subject: drm: avoid switching to text console if there is no panic timeout
has been added to the -mm tree.  Its filename is
     drm-avoid-switching-to-text-console-if-there-is-no-panic-timeout.patch

Where is mmotm hosted these days?

Regards,
Mandeep

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

[Dave Airlie]

On Thu, Nov 10, 2011 at 9:15 PM, Mandeep Singh Baines <msb@chromium.org> wrote:
> David Rientjes (rientjes@google.com) wrote:
>> On Mon, 17 Oct 2011, David Rientjes wrote:
>>
>> > On Mon, 17 Oct 2011, Mandeep Singh Baines 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.
>> > >
>> > > 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
>> >
>> > Acked-by: David Rientjes <rientjes@google.com>
>> >
>>
>> Dave, where do we stand on this?  I haven't seen it hit Linus' tree and I
>> don't see it in git://people.freedesktop.org/~airlied/linux.

I've just pulled it into my local drm-next, thanks for reminding me.

Dave.

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

[Andrew Morton]

On Thu, 10 Nov 2011 13:15:04 -0800
Mandeep Singh Baines <msb@chromium.org> wrote:

> David Rientjes (rientjes@google.com) wrote:
> > On Mon, 17 Oct 2011, David Rientjes wrote:
> > 
> > > On Mon, 17 Oct 2011, Mandeep Singh Baines 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.
> > > > 
> > > > 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
> > > 
> > > Acked-by: David Rientjes <rientjes@google.com>
> > > 
> > 
> > Dave, where do we stand on this?  I haven't seen it hit Linus' tree and I 
> > don't see it in git://people.freedesktop.org/~airlied/linux.
> 
> The last status I have is Andrew pulling it into mmotm on 10/18/11.
> 
> Subject: + drm-avoid-switching-to-text-console-if-there-is-no-panic-timeout.patch added to -mm tree
> From: akpm@linux-foundation.org
> Date: Tue, 18 Oct 2011 15:42:46 -0700
> 
> 
> The patch titled
>      Subject: drm: avoid switching to text console if there is no panic timeout
> has been added to the -mm tree.  Its filename is
>      drm-avoid-switching-to-text-console-if-there-is-no-panic-timeout.patch

I need to do another round of sending patches to maintainers.

It's a depressing exercise because the great majority of patches are
simply ignored.  Last time I even added "please don't ignore" to the
email Subject: on the more important ones.  Sigh.

> Where is mmotm hosted these days?

On my disk, until kernel.org ftp access returns.

But I regularly email tarballs to Stephen, so it's all in linux-next. 
The mmotm tree is largely unneeded now - use linux-next to get at -mm
patches.

Re: [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@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.
>
> 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>

Acked-by: Stéphane Marchesin <marcheu@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
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>

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

[Dave Young]

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

>
> 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
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>



-- 
Regards
Dave

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

[Dave Young]

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
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
>
>
>
> --
> Regards
> Dave
>



-- 
Regards
Dave

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

[Mandeep Singh Baines]

Dave Young (hidave.darkstar@gmail.com) wrote:
> 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
> 

Hi Dave,

I agree. The complexity is worth it if you want to see the panic trace
on the VT. But if you have the panic_timeout negative (i.e. reboot
immediately) than you're just add more risk/complexity to panic for no
benefit.


To avoid losing the panic traces, a reliable panic is critical.

In our app, we use panic_timeout=-1 and we use ramoops for capturing panic
traces. We want the panic path to be as simple as possible to avoid
wedging machines and to avoid losing panic traces. In our test lab,
if a machine gets wedged, a human needs to go and power cycle the machine
to bring it back online.

For user devices, we want to panic quickly and get the device back up
ASAP. Our reboot time is under 8 seconds so its less than 10 seconds before
you're back online and surfing the web. We also want to avoid displaying any
artifacts or traces to the user when panicking.

You bring up a good point about printk_delay. But I'm thinking if you're
using prink_delay you'd also want to set panic_timeout >= 0. Otherwise,
you'd reboot immediately after displaying the last line of output.

Regards,
Mandeep

> >
> >>
> >> 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
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >> Please read the FAQ at  http://www.tux.org/lkml/
> >>
> >
> >
> >
> > --
> > Regards
> > Dave
> >
> 
> 
> 
> -- 
> Regards
> Dave

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

[Dave Young]

On Wed, Oct 19, 2011 at 2:29 AM, Mandeep Singh Baines <msb@chromium.org> wrote:
> Dave Young (hidave.darkstar@gmail.com) wrote:
>> 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
>>
>
> Hi Dave,
>
> I agree. The complexity is worth it if you want to see the panic trace
> on the VT. But if you have the panic_timeout negative (i.e. reboot
> immediately) than you're just add more risk/complexity to panic for no
> benefit.
>
>
> To avoid losing the panic traces, a reliable panic is critical.
>
> In our app, we use panic_timeout=-1 and we use ramoops for capturing panic
> traces. We want the panic path to be as simple as possible to avoid
> wedging machines and to avoid losing panic traces. In our test lab,
> if a machine gets wedged, a human needs to go and power cycle the machine
> to bring it back online.
>
> For user devices, we want to panic quickly and get the device back up
> ASAP. Our reboot time is under 8 seconds so its less than 10 seconds before
> you're back online and surfing the web. We also want to avoid displaying any
> artifacts or traces to the user when panicking.
>
> You bring up a good point about printk_delay. But I'm thinking if you're
> using prink_delay you'd also want to set panic_timeout >= 0. Otherwise,
> you'd reboot immediately after displaying the last line of output.

fair enough, thanks.

>
> Regards,
> Mandeep
>
>> >
>> >>
>> >> 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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>> >> Please read the FAQ at  http://www.tux.org/lkml/
>> >>
>> >
>> >
>> >
>> > --
>> > Regards
>> > Dave
>> >
>>
>>
>>
>> --
>> Regards
>> Dave
>



-- 
Regards
Dave