On Wed, 29 Sep 2010, Dietz Pröpper wrote:
> if this is already known, feel free to ignore that mail.
Yes, it is a bug, and it was fixed in 2.6.36-rc. The fix is a bit big for
-stable, though, so I am delaying it until I am sure it doesn't cause any
problems.
Your thinkpad should not need thinkpad-acpi-style brightness control, is the
ACPI generic one, or the GPU one (through X.org) misbehaving?
Anyway, I will attach the relevant patch if you want to apply it to your
kernel.
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
>From f4332f65a6de960d5ca39bb44b05fb7fd6bed3f3 Mon Sep 17 00:00:00 2001
From: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
Date: Sat, 28 Aug 2010 17:50:22 -0300
Subject: [PATCH 1/6] thinkpad-acpi: find ACPI video device by synthetic HID
The Linux ACPI core locates the ACPI video devices for us and marks them
with ACPI_VIDEO_HID. Use that information to locate the video device
instead of a half-baked hunt for _BCL.
This uncouples the detection of the number of backlight brightness
levels on ThinkPads from the ACPI paths in vid_handle.
With this change, the driver should be able to always detect whether the
ThinkPad uses a 8-level or 16-level brightness scale even on newer
models for which the vid_handle paths have not been updated yet.
It will skip deactivated devices in the ACPI device tree, which is a
change in behaviour.
Signed-off-by: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
---
drivers/platform/x86/thinkpad_acpi.c | 52 ++++++++--------------------------
1 files changed, 12 insertions(+), 40 deletions(-)
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 4bdb137..eb44103 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6149,13 +6149,18 @@ static struct backlight_ops ibm_backlight_data = {
/* --------------------------------------------------------------------- */
+/*
+ * Call _BCL method of video device. On some ThinkPads this will
+ * switch the firmware to the ACPI brightness control mode.
+ */
+
static int __init tpacpi_query_bcl_levels(acpi_handle handle)
{
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
union acpi_object *obj;
int rc;
- if (ACPI_SUCCESS(acpi_evaluate_object(handle, NULL, NULL, &buffer))) {
+ if (ACPI_SUCCESS(acpi_evaluate_object(handle, "_BCL", NULL, &buffer))) {
obj = (union acpi_object *)buffer.pointer;
if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
printk(TPACPI_ERR "Unknown _BCL data, "
@@ -6172,55 +6177,22 @@ static int __init tpacpi_query_bcl_levels(acpi_handle handle)
return rc;
}
-static acpi_status __init tpacpi_acpi_walk_find_bcl(acpi_handle handle,
- u32 lvl, void *context, void **rv)
-{
- char name[ACPI_PATH_SEGMENT_LENGTH];
- struct acpi_buffer buffer = { sizeof(name), &name };
-
- if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer)) &&
- !strncmp("_BCL", name, sizeof(name) - 1)) {
- BUG_ON(!rv || !*rv);
- **(int **)rv = tpacpi_query_bcl_levels(handle);
- return AE_CTRL_TERMINATE;
- } else {
- return AE_OK;
- }
-}
/*
* Returns 0 (no ACPI _BCL or _BCL invalid), or size of brightness map
*/
static unsigned int __init tpacpi_check_std_acpi_brightness_support(void)
{
- int status;
+ acpi_handle video_device;
int bcl_levels = 0;
- void *bcl_ptr = &bcl_levels;
- if (!vid_handle)
- TPACPI_ACPIHANDLE_INIT(vid);
+ tpacpi_acpi_handle_locate("video", ACPI_VIDEO_HID, &video_device);
+ if (video_device)
+ bcl_levels = tpacpi_query_bcl_levels(video_device);
- if (!vid_handle)
- return 0;
-
- /*
- * Search for a _BCL method, and execute it. This is safe on all
- * ThinkPads, and as a side-effect, _BCL will place a Lenovo Vista
- * BIOS in ACPI backlight control mode. We do NOT have to care
- * about calling the _BCL method in an enabled video device, any
- * will do for our purposes.
- */
+ tp_features.bright_acpimode = (bcl_levels > 0);
- status = acpi_walk_namespace(ACPI_TYPE_METHOD, vid_handle, 3,
- tpacpi_acpi_walk_find_bcl, NULL, NULL,
- &bcl_ptr);
-
- if (ACPI_SUCCESS(status) && bcl_levels > 2) {
- tp_features.bright_acpimode = 1;
- return bcl_levels - 2;
- }
-
- return 0;
+ return (bcl_levels > 2) ? (bcl_levels - 2) : 0;
}
/*
--
1.7.2.3
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