2012-06-25 11:50:15

by David Airlie

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.

[airlied: this is breaking nouveau really badly on 3.4 and after and there is
no movement on sending it upstream, so please apply]

Cc: Igor Murzov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Zhang Rui <[email protected]>
---
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;
}

2012-06-26 02:02:06

by Zhang, Rui

Subject: Re: Still use ACPI backlight control if _DOS doesn't exist

Hi, Dave,

How about this one, which I think is better? :)
http://marc.info/?l=linux-acpi&m=134015703925079&w=2

can you give it a try?

thanks,
rui

On 一, 2012-06-25 at 12:38 +0100, Dave Airlie wrote:
> 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.
>
> [airlied: this is breaking nouveau really badly on 3.4 and after and there is
> no movement on sending it upstream, so please apply]
>
> Cc: Igor Murzov <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Zhang Rui <[email protected]>
> ---
> 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;
> }