Based on analysis and a patch from Matthew Garrett <mjg59@xxxxxxxxxxxxx>.
Instruct the ThinkPad ACPI firmware to remove delays on the processing of
backlight brightness changes. This method is present on ThinkPad
Vista-compatible BIOSes with standard ACPI backlight level control.
Signed-off-by: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx>
Cc: Yves-Alexis Perez <corsac@xxxxxxxxxx>
---
drivers/misc/thinkpad_acpi.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index 4c47f9b..17b8281 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -838,6 +838,13 @@ static int parse_strtoul(const char *buf,
return 0;
}
+static void tpacpi_disable_brightness_delay(void)
+{
+ if (acpi_evalf(hkey_handle, NULL, "PWMS", "qvd", 0))
+ printk(TPACPI_NOTICE
+ "ACPI backlight control delay disabled\n");
+}
+
static int __init tpacpi_query_bcl_levels(acpi_handle handle)
{
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
@@ -2139,6 +2146,8 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
if (!tp_features.hotkey)
return 1;
+ tpacpi_disable_brightness_delay();
+
hotkey_dev_attributes = create_attr_set(13, NULL);
if (!hotkey_dev_attributes)
return -ENOMEM;
@@ -2512,6 +2521,8 @@ static void hotkey_suspend(pm_message_t state)
static void hotkey_resume(void)
{
+ tpacpi_disable_brightness_delay();
+
if (hotkey_mask_get())
printk(TPACPI_ERR
"error while trying to read hot key mask "
--
1.5.6.5
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