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ACPI: thinkpad-acpi: fix brightness dimming control bug

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ibm-acpi and thinkpad-acpi did not know about bit 5 of the EC backlight
level control register (EC 0x31), so it was always forced to zero on
any writes.

This would disable the BIOS option to *not* use a dimmer backlight level
scale while on battery, and who knows what else (there are two other
control bits of unknown function).

Bit 5 controls the "reduce backlight levels when on battery" optional
functionality (active low).  Bits 6 and 7 are better left alone as well,
instead of being forced to zero.

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 2008-04-26 01:02:21 -03:00 committed by Len Brown
parent 2d5e94d7ca
commit e11aecf137
1 changed files with 49 additions and 15 deletions
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64
drivers/misc/thinkpad_acpi.c
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@ -4295,8 +4295,16 @@ static struct ibm_struct ecdump_driver_data = {
#define TPACPI_BACKLIGHT_DEV_NAME "thinkpad_screen"
enum {
TP_EC_BACKLIGHT = 0x31,
/* TP_EC_BACKLIGHT bitmasks */
TP_EC_BACKLIGHT_LVLMSK = 0x1F,
TP_EC_BACKLIGHT_CMDMSK = 0xE0,
TP_EC_BACKLIGHT_MAPSW = 0x20,
};
static struct backlight_device *ibm_backlight_device;
static int brightness_offset = 0x31;
static int brightness_mode;
static unsigned int brightness_enable = 2; /* 2 = auto, 0 = no, 1 = yes */
@ -4305,16 +4313,24 @@ static struct mutex brightness_mutex;
/*
* ThinkPads can read brightness from two places: EC 0x31, or
* CMOS NVRAM byte 0x5E, bits 0-3.
*
* EC 0x31 has the following layout
* Bit 7: unknown function
* Bit 6: unknown function
* Bit 5: Z: honour scale changes, NZ: ignore scale changes
* Bit 4: must be set to zero to avoid problems
* Bit 3-0: backlight brightness level
*
* brightness_get_raw returns status data in the EC 0x31 layout
*/
static int brightness_get(struct backlight_device *bd)
static int brightness_get_raw(int *status)
{
u8 lec = 0, lcmos = 0, level = 0;
if (brightness_mode & 1) {
if (!acpi_ec_read(brightness_offset, &lec))
if (!acpi_ec_read(TP_EC_BACKLIGHT, &lec))
return -EIO;
lec &= (tp_features.bright_16levels)? 0x0f : 0x07;
level = lec;
level = lec & TP_EC_BACKLIGHT_LVLMSK;
};
if (brightness_mode & 2) {
lcmos = (nvram_read_byte(TP_NVRAM_ADDR_BRIGHTNESS)
@ -4325,6 +4341,8 @@ static int brightness_get(struct backlight_device *bd)
}
if (brightness_mode == 3) {
*status = lec; /* Prefer EC, CMOS is just a backing store */
lec &= TP_EC_BACKLIGHT_LVLMSK;
if (lec == lcmos)
tp_warned.bright_cmos_ec_unsync = 0;
else {
@ -4338,9 +4356,11 @@ static int brightness_get(struct backlight_device *bd)
}
return -EIO;
}
} else {
*status = level;
}
return level;
return 0;
}
/* May return EINTR which can always be mapped to ERESTARTSYS */
@ -4348,19 +4368,22 @@ static int brightness_set(int value)
{
int cmos_cmd, inc, i, res;
int current_value;
int command_bits;
if (value > ((tp_features.bright_16levels)? 15 : 7))
if (value > ((tp_features.bright_16levels)? 15 : 7) ||
value < 0)
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;
res = brightness_get_raw(&current_value);
if (res < 0)
goto errout;
}
command_bits = current_value & TP_EC_BACKLIGHT_CMDMSK;
current_value &= TP_EC_BACKLIGHT_LVLMSK;
cmos_cmd = value > current_value ?
TP_CMOS_BRIGHTNESS_UP :
@ -4375,7 +4398,8 @@ static int brightness_set(int value)
goto errout;
}
if ((brightness_mode & 1) &&
!acpi_ec_write(brightness_offset, i + inc)) {
!acpi_ec_write(TP_EC_BACKLIGHT,
(i + inc) | command_bits)) {
res = -EIO;
goto errout;;
}
@ -4398,6 +4422,17 @@ static int brightness_update_status(struct backlight_device *bd)
bd->props.brightness : 0);
}
static int brightness_get(struct backlight_device *bd)
{
int status, res;
res = brightness_get_raw(&status);
if (res < 0)
return 0; /* FIXME: teach backlight about error handling */
return status & TP_EC_BACKLIGHT_LVLMSK;
}
static struct backlight_ops ibm_backlight_data = {
.get_brightness = brightness_get,
.update_status = brightness_update_status,
@ -4462,8 +4497,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
if (brightness_mode > 3)
return -EINVAL;
b = brightness_get(NULL);
if (b < 0)
if (brightness_get_raw(&b) < 0)
return 1;
if (tp_features.bright_16levels)
@ -4481,7 +4515,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
ibm_backlight_device->props.max_brightness =
(tp_features.bright_16levels)? 15 : 7;
ibm_backlight_device->props.brightness = b;
ibm_backlight_device->props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
backlight_update_status(ibm_backlight_device);
return 0;