diff options
| -rw-r--r-- | Documentation/laptops/thinkpad-acpi.txt | 14 | ||||
| -rw-r--r-- | drivers/platform/x86/thinkpad_acpi.c | 10 |
2 files changed, 18 insertions, 6 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index 88fc0661de5..f2ff638cce8 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -1169,17 +1169,19 @@ may not be distinct. Later Lenovo models that implement the ACPI display backlight brightness control methods have 16 levels, ranging from 0 to 15. -There are two interfaces to the firmware for direct brightness control, -EC and UCMS (or CMOS). To select which one should be used, use the -brightness_mode module parameter: brightness_mode=1 selects EC mode, -brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC -mode with NVRAM backing (so that brightness changes are remembered -across shutdown/reboot). +For IBM ThinkPads, there are two interfaces to the firmware for direct +brightness control, EC and UCMS (or CMOS). To select which one should be +used, use the brightness_mode module parameter: brightness_mode=1 selects +EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC +mode with NVRAM backing (so that brightness changes are remembered across +shutdown/reboot). The driver tries to select which interface to use from a table of defaults for each ThinkPad model. If it makes a wrong choice, please report this as a bug, so that we can fix it. +Lenovo ThinkPads only support brightness_mode=2 (UCMS). + When display backlight brightness controls are available through the standard ACPI interface, it is best to use it instead of this direct ThinkPad-specific interface. The driver will disable its native diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c index 5a22a064222..c8d74dbacbb 100644 --- a/drivers/platform/x86/thinkpad_acpi.c +++ b/drivers/platform/x86/thinkpad_acpi.c @@ -5696,6 +5696,10 @@ static struct ibm_struct ecdump_driver_data = { * Bit 3-0: backlight brightness level * * brightness_get_raw returns status data in the HBRV layout + * + * WARNING: The X61 has been verified to use HBRV for something else, so + * this should be used _only_ on IBM ThinkPads, and maybe with some careful + * testing on the very early *60 Lenovo models... */ enum { @@ -5996,6 +6000,12 @@ static int __init brightness_init(struct ibm_init_struct *iibm) brightness_mode); } + /* Safety */ + if (thinkpad_id.vendor != PCI_VENDOR_ID_IBM && + (brightness_mode == TPACPI_BRGHT_MODE_ECNVRAM || + brightness_mode == TPACPI_BRGHT_MODE_EC)) + return -EINVAL; + if (tpacpi_brightness_get_raw(&b) < 0) return 1; |