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ACPI: thinkpad-acpi: add locking to brightness subdriver

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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>
This commit is contained in:
Henrique de Moraes Holschuh 2007-07-18 23:45:48 -03:00 committed by Len Brown
parent c78d5c96bb
commit f432255e93
1 changed files with 28 additions and 7 deletions
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35
drivers/misc/thinkpad_acpi.c
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@ -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)