Message-ID: <52FE2C95.60302@intel.com>
Date: Fri, 14 Feb 2014 22:47:49 +0800
From: Aaron Lu <aaron.lu@intel.com>
MIME-Version: 1.0
To: Takashi Iwai <tiwai@suse.de>,
        Mika Westerberg <mika.westerberg@linux.intel.com>
CC: linux-acpi@vger.kernel.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "ACPI / video: Add HP EliteBook Revolve 810 to
 the blacklist"
References: <1392381247-28109-1-git-send-email-mika.westerberg@linux.intel.com>	<s5hmwht24ub.wl%tiwai@suse.de>	<20140214140316.GI5018@intel.com> <s5hfvnl23pq.wl%tiwai@suse.de>
In-Reply-To: <s5hfvnl23pq.wl%tiwai@suse.de>
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Sender: linux-kernel-owner@vger.kernel.org

On 02/14/2014 10:01 PM, Takashi Iwai wrote:
> At Fri, 14 Feb 2014 16:03:16 +0200,
> Mika Westerberg wrote:
>>
>> On Fri, Feb 14, 2014 at 02:37:00PM +0100, Takashi Iwai wrote:
>>> At Fri, 14 Feb 2014 14:34:07 +0200,
>>> Mika Westerberg wrote:
>>>>
>>>> This reverts commit e18ac62fa4b3f16234bab0d5a6627c57dbae9e7e.
>>>>
>>>> The referenced commit added HP EliteBook Revolve 810 to the ACPI video
>>>> detected blacklist so that only the native Intel backlight interface was
>>>> exported.
>>>>
>>>> However, this turned to be wrong solution after all. The ACPI video
>>>> interface works and as long as we only use that there are no problems. So
>>>> we can revert this commit and stick to use the backlight interface provided
>>>> by the ACPI video driver.
>>>>
>>>> (Using Intel native interface will not work after resume since the ACPI
>>>> video driver will restore it's state which takes control over the native
>>>> one. That's a separate thing and should be addressed in the ACPI video
>>>> driver, I suppose.)
>>>>
>>>> References: https://bugzilla.kernel.org/show_bug.cgi?id=70231
>>>> Cc: Aaron Lu <aaron.lu@intel.com>
>>>> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
>>>> ---
>>>> Rafael, 
>>>>
>>>> This turned out to be misunderstanding from my side. I should have
>>>> investigated this further before submitting the original patch. Sorry about
>>>> that.
>>>>
>>>> Aaron,
>>>>
>>>> Thanks for the investigation and pointing me to the right direction (e.g to
>>>> use acpi_video0 over the native one).
>>>
>>> Could you check whether the ACPI video still really works even if you
>>> remove the recent acpi_osi blacklist entry below?  It might be that
>>> BIOS changed its mind to behave more kindly as if handling for Win7.
>>>
>>>
>>> Takashi
>>>
>>> ---
>>> diff --git a/drivers/acpi/blacklist.c b/drivers/acpi/blacklist.c
>>> index 10e4964d051a..64d14406465d 100644
>>> --- a/drivers/acpi/blacklist.c
>>> +++ b/drivers/acpi/blacklist.c
>>> @@ -322,6 +322,7 @@ static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
>>>  		     DMI_MATCH(DMI_PRODUCT_VERSION, "2349D15"),
>>>  		},
>>>  	},
>>> +#if 0
>>>  	{
>>>  	.callback = dmi_disable_osi_win8,
>>>  	.ident = "HP ProBook 2013 models",
>>> @@ -372,6 +373,7 @@ static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
>>>  		     DMI_MATCH(DMI_PRODUCT_NAME, "HP EliteBook 8780w"),
>>>  		},
>>>  	},
>>> +#endif
>>>  
>>>  	/*
>>>  	 * BIOS invocation of _OSI(Linux) is almost always a BIOS bug.
>>
>> After this patch is applied, the ACPI backlight doesn't work anymore. The
>> brightness stays the same, no matter what I do.
> 
> So, you need the video blacklist when acpi_osi blacklist doesn't
> exist, right?

Yes, but not in the video_detect DMI table. A table for systems
that should favour native backlight control interface should be
used in this case. Or we can simply make all Win8 systems favour
native backlight control interface in video module. That is the
decision we need to make then.
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