linux-hwg/3.4.4-fix-backlight-regression.patch

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2012-06-24 19:48:49 +02:00
Subject: Still use ACPI backlight control if _DOS doesn't exist
This is a regression introduced by commit
ea9f8856bd6d4ed45885b06a338f7362cd6c60e5
https://bugzilla.kernel.org/show_bug.cgi?id=43168
Some platforms don't have _DOS control method, but the ACPI
backlight still works.
We do not want to lose the backlight control ability on these platforms.
CC : Igor Murzov <intergalactic.anonymous@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
---
drivers/acpi/video.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
Index: rtd3/drivers/acpi/video.c
===================================================================
--- rtd3.orig/drivers/acpi/video.c
+++ rtd3/drivers/acpi/video.c
@@ -565,8 +565,14 @@ acpi_video_bus_DOS(struct acpi_video_bus
video->dos_setting = arg0.integer.value;
status = acpi_evaluate_object(video->device->handle, "_DOS",
&args, NULL);
- if (ACPI_FAILURE(status))
- return -EIO;
+ if (ACPI_FAILURE(status)) {
+ /*
+ * some platforms don't have _DOS, but the ACPI
+ * backlight control still works
+ */
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _DOS\n"));
+ return 0;
+ }
return 0;
}