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authorHenrique de Moraes Holschuh <hmh@hmh.eng.br>2007-07-18 23:45:48 -0300
committerLen Brown <len.brown@intel.com>2007-07-21 23:50:51 -0400
commitf432255e936a892a6896e5032e2b4897423076f2 (patch)
treece32df538477acab984d079d6963e0261c0d7325 /drivers/misc
parentc78d5c96bb65b71a54b7551b404fbaf4763ed6e4 (diff)
downloadlinux-f432255e936a892a6896e5032e2b4897423076f2.tar.bz2
ACPI: thinkpad-acpi: add locking to brightness subdriver
The backlight class does all the locking needed for sysfs access, but offers no API to interface to that locking without an layer violation. Since we need to mutex-lock procfs access, implement in-driver locking for brightness. It will go away the day thinkpad-acpi procfs goes away, or the backlight class gives us a way to use its locks without a layer violation. Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/thinkpad_acpi.c35
1 files changed, 28 insertions, 7 deletions
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 01bed937d387..f15a58f7403f 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -3000,12 +3000,16 @@ static struct backlight_ops ibm_backlight_data = {
.update_status = brightness_update_status,
};
+static struct mutex brightness_mutex;
+
static int __init brightness_init(struct ibm_init_struct *iibm)
{
int b;
vdbg_printk(TPACPI_DBG_INIT, "initializing brightness subdriver\n");
+ mutex_init(&brightness_mutex);
+
if (!brightness_mode) {
if (thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO)
brightness_mode = 2;
@@ -3092,27 +3096,44 @@ static int brightness_get(struct backlight_device *bd)
static int brightness_set(int value)
{
- int cmos_cmd, inc, i;
- int current_value = brightness_get(NULL);
+ int cmos_cmd, inc, i, res;
+ int current_value;
if (value > 7)
return -EINVAL;
+ res = mutex_lock_interruptible(&brightness_mutex);
+ if (res < 0)
+ return res;
+
+ current_value = brightness_get(NULL);
+ if (current_value < 0) {
+ res = current_value;
+ goto errout;
+ }
+
cmos_cmd = value > current_value ?
TP_CMOS_BRIGHTNESS_UP :
TP_CMOS_BRIGHTNESS_DOWN;
inc = value > current_value ? 1 : -1;
+ res = 0;
for (i = current_value; i != value; i += inc) {
if ((brightness_mode & 2) &&
- issue_thinkpad_cmos_command(cmos_cmd))
- return -EIO;
+ issue_thinkpad_cmos_command(cmos_cmd)) {
+ res = -EIO;
+ goto errout;
+ }
if ((brightness_mode & 1) &&
- !acpi_ec_write(brightness_offset, i + inc))
- return -EIO;
+ !acpi_ec_write(brightness_offset, i + inc)) {
+ res = -EIO;
+ goto errout;;
+ }
}
- return 0;
+errout:
+ mutex_unlock(&brightness_mutex);
+ return res;
}
static int brightness_read(char *p)