lkml.org 
[lkml]   [2006]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: backlight: oops in __mutex_lock_slowpath during head /sys/class/graphics/fb0/* in 2.6.18
On Thu, Sep 21, 2006 at 12:37:42PM -0700, Andrew Morton wrote:
> On Thu, 21 Sep 2006 14:19:52 +0200
> Olaf Hering <olaf@aepfle.de> wrote:
> > The bl_curve code has some room for improvement.

Agreed.

> > inst-sys:~ # dmesg
> > valkyriefb: vmode 13 does not support cmode 1.
> > Unable to handle kernel paging request for data at address 0x00000000
> > Faulting instruction address: 0xc02c7bd8

Seems like not all drivers use the framebuffer_alloc() function and
won't have an initialized mutex. But those don't have a backlight,
anyway.

What about the patch below? Does it work for you?

Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>

---
diff -Nrup --exclude-from linux-exclude-from linux-2.6.18.orig/drivers/video/fbsysfs.c linux-2.6.18/drivers/video/fbsysfs.c
--- linux-2.6.18.orig/drivers/video/fbsysfs.c 2006-09-21 23:40:06.000000000 +0200
+++ linux-2.6.18/drivers/video/fbsysfs.c 2006-09-21 23:50:00.000000000 +0200
@@ -397,6 +397,12 @@ static ssize_t store_bl_curve(struct cla
u8 tmp_curve[FB_BACKLIGHT_LEVELS];
unsigned int i;

+ /* Some drivers don't use framebuffer_alloc(), but those also
+ * don't have backlights.
+ */
+ if (!fb_info || !fb_info->bl_dev)
+ return -ENODEV;
+
if (count != (FB_BACKLIGHT_LEVELS / 8 * 24))
return -EINVAL;

@@ -430,6 +436,12 @@ static ssize_t show_bl_curve(struct clas
ssize_t len = 0;
unsigned int i;

+ /* Some drivers don't use framebuffer_alloc(), but those also
+ * don't have backlights.
+ */
+ if (!fb_info || !fb_info->bl_dev)
+ return -ENODEV;
+
mutex_lock(&fb_info->bl_mutex);
for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8)
len += snprintf(&buf[len], PAGE_SIZE,
-
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/
\
 
 \ /
  Last update: 2006-09-22 00:01    [W:0.044 / U:0.216 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site