linux-kernel - Re: [PATCH] Platform: samsung-laptop: add DMI information for Samsung N150 Plus

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Date:	Thu, 29 Dec 2011 11:23:36 +0100
From:	Corentin Chary <corentin.chary@...il.com>
To:	David Herrmann <dh.herrmann@...glemail.com>
CC:	Matthew Garrett <mjg59@...f.ucam.org>,
	Andrzej Prochyra <andrzej@...chyra.name>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Zhang, Rui" <rui.zhang@...el.com>
Subject: Re: [PATCH] Platform: samsung-laptop: add DMI information for Samsung
 N150 Plus

On 12/26/2011 11:22 AM, David Herrmann wrote:
> On Mon, Dec 26, 2011 at 10:49 AM, Corentin Chary
> <corentin.chary@...il.com>  wrote:
>> On Sat, Dec 24, 2011 at 3:28 PM, David Herrmann
>> <dh.herrmann@...glemail.com>  wrote:
>>> On Sat, Dec 24, 2011 at 3:20 PM, Matthew Garrett<mjg59@...f.ucam.org>  wrote:
>>>> On Sat, Dec 24, 2011 at 02:12:57PM +0000, Andrzej Prochyra wrote:
>>>>> 'acpi_video0' not functional.  Brightness can be controlled through
>>>>> intel_backlight interface.  There are 21 brightness levels and the
>>>>> backlight can be turned off.
>>>>
>>>> If acpi_video0 doesn't work then we either need to work out why it's not
>>>> working or make it vanish completely, so this patch isn't the correct
>>>> approach.
>>>
>>> Just to make clear, intel_backlight isn't working properly either. If
>>> my laptop boots with backlight at 50% then intel_backlight will only
>>> work in the range 0%-50% on my machine. If I use the samsung module to
>>> set it to 100% then  intel_backlight works correctly in the range
>>> 0-100% until next reboot/suspend.
>>>
>>> So I'd recommend staying with the samsung module and disabling the
>>> acpi_backlight entirely. The samsung module is the only backlight
>>> control which works properly.
>>
>> Can I take a look at the DSDT to see how it's broken ?
>> If it's really not functional, then it should be added to the
>> blacklist in video_detect.c
>
> Raw and disassembled dsdt is attached.

Took a quick look but didn't find anything obvious. What happens exactly 
with acpi_video0 ?

But if it's not possible to make it work, I'd propose that (not tested):

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 45d8097..5041924 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -132,6 +132,26 @@ find_video(acpi_handle handle, u32 lvl, void 
*context, void **rv)
         return AE_OK;
  }

+/* Force to use vendor driver when the ACPI device is known to be
+ * buggy */
+static int video_detect_force_vendor(const struct dmi_system_id *d)
+{
+       acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
+}
+
+static struct dmi_system_id video_detect_dmi_table[] __initdata = {
+       {
+        .callback = video_detect_force_vendor,
+        .ident = "N150P",
+        .matches = {
+               DMI_MATCH(DMI_SYS_VENDOR,
+                         "SAMSUNG ELECTRONICS CO., LTD."),
+               DMI_MATCH(DMI_PRODUCT_NAME, "N150P"),
+               DMI_MATCH(DMI_BOARD_NAME, "N150P"),
+               },
+       },
+};
+
  /*
   * Returns the video capabilities of a specific ACPI graphics device
   *
@@ -164,6 +184,8 @@ long acpi_video_get_capabilities(acpi_handle 
graphics_handle)
                  *              ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
                  *}
                  */
+
+               dmi_check_system(video_detect_dmi_table);
         } else {
                 status = acpi_bus_get_device(graphics_handle, &tmp_dev);
                 if (ACPI_FAILURE(status)) {


-- 
Corentin Chary
http://xf.iksaif.net/
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