From d68752cf7bb92eafbbe6a0df0d0fab67e87523f6 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@chromium.org>
Date: Mon, 17 Oct 2011 17:06:40 -0700
Subject: [PATCH] drm: avoid switching to text console if there is no panic
timeout
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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: David Rientjes <rientjes@google.com>
Acked-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
---
drivers/gpu/drm/drm_fb_helper.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 80fe39d98b0c2..aada26f63decc 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -255,6 +255,13 @@ 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();
}
--
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