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 <coproscefalo@xxxxxxxxx>
---
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
--
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