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Date: Thu, 12 Jun 2008 18:00:06 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: "Julia Jomantaite" <julia.jomantaite@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
Zhang Rui <rui.zhang@...el.com>
Subject: Re: [PATCH] drivers/acpi/video: fix brightness allocation
On Thu, 12 Jun 2008 17:47:09 +0100
"Julia Jomantaite" <julia.jomantaite@...il.com> wrote:
> ACPI Video Driver module (drivers/acpi/video.c) produces Oops message
> after pressing one of two Fn+<key> combinations responsible for switching
> the brightness level on my laptop.
>
> The source of this problem is in the function acpi_video_switch_brightness
> which can access device->brightness when it is not allocated. Function
> "acpi_video_device_find_cap" which is responsible for allocating
> device->brightness can leave it unallocated in some cases.
>
> Function acpi_video_switch_brightness isn't called if modules's parameter
> "brightness_switch_enabled" is equal to zero so i've decided to add
> zeroing of this parameter to the part of the code where unsuccessfull
> allocation of device->brightness was handled.
>
> Also i've moved initialization of brightness to a separate function
> "acpi_video_init_brightness" to improve readability of the code and
> to simplify error handling.
>
(cc's added)
Thanks. Which kernel version were you running?
The patch was a bit wordwrapped. Here's the fixed up version:
drivers/acpi/video.c | 122 ++++++++++++++++++++++++-----------------
1 file changed, 72 insertions(+), 50 deletions(-)
diff -puN drivers/acpi/video.c~drivers-acpi-video-fix-brightness-allocation drivers/acpi/video.c
--- a/drivers/acpi/video.c~drivers-acpi-video-fix-brightness-allocation
+++ a/drivers/acpi/video.c
@@ -631,6 +631,74 @@ acpi_video_bus_DOS(struct acpi_video_bus
* device : video output device (LCD, CRT, ..)
*
* Return Value:
+ * Maximum brightness level
+ *
+ * Allocate and initialize device->brightness.
+ */
+
+static int
+acpi_video_init_brightness(struct acpi_video_device *device)
+{
+ union acpi_object *obj = NULL;
+ int i, max_level = 0, count = 0;
+ union acpi_object *o;
+ struct acpi_video_device_brightness *br = NULL;
+
+ if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available LCD brightness level\n"));
+ goto out;
+ }
+
+ if (obj->package.count < 2)
+ goto out;
+
+ br = kzalloc(sizeof(*br), GFP_KERNEL);
+ if (!br) {
+ printk(KERN_ERR "can't allocate memory\n");
+ goto out;
+ }
+
+ br->levels = kmalloc(obj->package.count * sizeof *(br->levels), GFP_KERNEL);
+ if (!br->levels)
+ goto out_free;
+
+ for (i = 0; i < obj->package.count; i++) {
+ o = (union acpi_object *)&obj->package.elements[i];
+ if (o->type != ACPI_TYPE_INTEGER) {
+ printk(KERN_ERR PREFIX "Invalid data\n");
+ continue;
+ }
+ br->levels[count] = (u32) o->integer.value;
+
+ if (br->levels[count] > max_level)
+ max_level = br->levels[count];
+ count++;
+ }
+
+ if (count < 2)
+ goto out_free_levels;
+
+ br->count = count;
+ device->brightness = br;
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "found %d brightness levels\n", count));
+ kfree(obj);
+ return max_level;
+
+out_free_levels:
+ kfree(br->levels);
+out_free:
+ kfree(br);
+out:
+ brightness_switch_enabled = 0;
+ kfree(obj);
+ return 0;
+}
+
+/*
+ * Arg:
+ * device : video output device (LCD, CRT, ..)
+ *
+ * Return Value:
* None
*
* Find out all required AML methods defined under the output
@@ -640,10 +708,7 @@ acpi_video_bus_DOS(struct acpi_video_bus
static void acpi_video_device_find_cap(struct acpi_video_device *device)
{
acpi_handle h_dummy1;
- int i;
u32 max_level = 0;
- union acpi_object *obj = NULL;
- struct acpi_video_device_brightness *br = NULL;
memset(&device->cap, 0, sizeof(device->cap));
@@ -657,8 +722,9 @@ static void acpi_video_device_find_cap(s
if (ACPI_SUCCESS(acpi_get_handle(device->dev->handle, "_BCM", &h_dummy1))) {
device->cap._BCM = 1;
}
- if (ACPI_SUCCESS(acpi_get_handle(device->dev->handle,"_BQC",&h_dummy1)))
+ if (ACPI_SUCCESS(acpi_get_handle(device->dev->handle, "_BQC", &h_dummy1))) {
device->cap._BQC = 1;
+ }
if (ACPI_SUCCESS(acpi_get_handle(device->dev->handle, "_DDC", &h_dummy1))) {
device->cap._DDC = 1;
}
@@ -672,54 +738,10 @@ static void acpi_video_device_find_cap(s
device->cap._DSS = 1;
}
- if (ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
-
- if (obj->package.count >= 2) {
- int count = 0;
- union acpi_object *o;
-
- br = kzalloc(sizeof(*br), GFP_KERNEL);
- if (!br) {
- printk(KERN_ERR "can't allocate memory\n");
- } else {
- br->levels = kmalloc(obj->package.count *
- sizeof *(br->levels), GFP_KERNEL);
- if (!br->levels)
- goto out;
-
- for (i = 0; i < obj->package.count; i++) {
- o = (union acpi_object *)&obj->package.
- elements[i];
- if (o->type != ACPI_TYPE_INTEGER) {
- printk(KERN_ERR PREFIX "Invalid data\n");
- continue;
- }
- br->levels[count] = (u32) o->integer.value;
-
- if (br->levels[count] > max_level)
- max_level = br->levels[count];
- count++;
- }
- out:
- if (count < 2) {
- kfree(br->levels);
- kfree(br);
- } else {
- br->count = count;
- device->brightness = br;
- ACPI_DEBUG_PRINT((ACPI_DB_INFO,
- "found %d brightness levels\n",
- count));
- }
- }
- }
-
- } else {
- ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available LCD brightness level\n"));
+ if (brightness_switch_enabled) {
+ max_level = acpi_video_init_brightness(device);
}
- kfree(obj);
-
if (device->cap._BCL && device->cap._BCM && device->cap._BQC && max_level > 0){
int result;
static int count = 0;
_
--
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