Some Toshiba models (most notably Qosmios) come with an incomplete backlight method where the AML code doesn't check for write or read commands and always returns HCI_SUCCESS and the actual brightness (and in some cases the max brightness), thus allowing the backlight interface to be registered without write support.
This patch changes the set_lcd_brightness function, checking the returned values for values greater than zero to avoid registering a broken backlight interface. Signed-off-by: Azael Avalos <[email protected]> --- drivers/platform/x86/toshiba_acpi.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c index 76441dc..1ed2ffc 100644 --- a/drivers/platform/x86/toshiba_acpi.c +++ b/drivers/platform/x86/toshiba_acpi.c @@ -872,7 +872,9 @@ static int lcd_proc_open(struct inode *inode, struct file *file) static int set_lcd_brightness(struct toshiba_acpi_dev *dev, int value) { - u32 hci_result; + u32 in[HCI_WORDS] = { HCI_SET, HCI_LCD_BRIGHTNESS, 0, 0, 0, 0 }; + u32 out[HCI_WORDS]; + acpi_status status; if (dev->tr_backlight_supported) { bool enable = !value; @@ -883,9 +885,20 @@ static int set_lcd_brightness(struct toshiba_acpi_dev *dev, int value) value--; } - value = value << HCI_LCD_BRIGHTNESS_SHIFT; - hci_write1(dev, HCI_LCD_BRIGHTNESS, value, &hci_result); - return hci_result == HCI_SUCCESS ? 0 : -EIO; + in[2] = value << HCI_LCD_BRIGHTNESS_SHIFT; + status = hci_raw(dev, in, out); + if (ACPI_FAILURE(status) || out[0] == HCI_FAILURE) { + pr_err("ACPI call to set brightness failed"); + return -EIO; + } + /* Extra check for "incomplete" backlight method, where the AML code + * doesn't check for HCI_SET or HCI_GET and returns HCI_SUCCESS, + * the actual brightness, and in some cases the max brightness. + */ + if (out[2] > 0 || out[3] == 0xE000) + return -ENODEV; + + return out[0] == HCI_SUCCESS ? 0 : -EIO; } static int set_lcd_status(struct backlight_device *bd) -- 2.0.0 -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
