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Subject: Re: platform/x86: asus-wmi: SW_TABLET_MODE is always 1 on some
 devices
To:     =?UTF-8?Q?Samuel_=c4=8cavoj?= <samuel@cavoj.net>
Cc:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Corentin Chary <corentin.chary@gmail.com>,
        acpi4asus-user@lists.sourceforge.net,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20200901215536.qcouepovmfxje4n5@fastboi.localdomain>
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 <320c0b71-af94-c673-21c8-c32a0fdb4d4e@redhat.com>
 <20200904171743.ejew22p3zzada55p@fastboi.localdomain>
 <a21a6fbf-f38b-3531-07f4-74edd0e42eb6@redhat.com>
 <20200910223129.epmeyvodj6agnzav@fastboi.localdomain>
From:   Hans de Goede <hdegoede@redhat.com>
Message-ID: <f0a48bbb-ab10-ce2c-c973-617af7fdae8f@redhat.com>
Date:   Fri, 11 Sep 2020 15:24:54 +0200
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Hi,

On 9/11/20 12:31 AM, Samuel Čavoj wrote:
> Hello!
> 
> On 10.09.2020 19:44, Hans de Goede wrote:
>> Hi,
>>
>> On 9/4/20 7:17 PM, Samuel Čavoj wrote:
>>> Hi,
>>>
>>> On 04.09.2020 12:06, Hans de Goede wrote:
>>>> Hi,
>>>>
>>>> On 9/4/20 11:45 AM, Samuel Čavoj wrote:
>>>>> Hello!
>>>>>
>>>>> On 02.09.2020 14:52, Samuel Čavoj wrote:
>>>>>> Hello,
>>>>>>
>>>>>> On 02.09.2020 13:52, Hans de Goede wrote:
>>>>>>> But I would rather try to figure out a better way. Can you
>>>>>>> create an acpidump, by as root running:
>>>>>>>
>>>>>>> acpidump -o acpidump.asus-UX360CA
>>>>>>
>>>>>> The file is attached gzipped.
>>>>>>
>>>>>>>
>>>>>>> And then send me a direct (so without including the list)
>>>>>>> email with the generated acpidump.asus-UX360CA file attached please?
>>>>>>>
>>>>>>> Also, if necessary are you capable of building your own
>>>>>>> kernel with a (test)patch applied ?
>>>>>>
>>>>>> Yes, that is no problem at all.
>>>>>> Thank you for your quick response.
>>>>>>
>>>>>> Regards,
>>>>>> Samuel
>>>>>
>>>>> I don't mean to waste your time, it's just that my trust in mail systems
>>>>> has been steadily decreasing. I would just like to make sure you have
>>>>> received my previous email with the acpidump.
>>>>>
>>>>> In case not, here[1] it is available over https, if the message got
>>>>> dropped because of the attachment.
>>>>
>>>> I got your mail, but I've been burried under a ton of work,
>>>> so it may take a couple of days at least before I can take
>>>> a closer look at this.
>>>
>>> That's quite alright.
>>>
>>> I decided I would try and see if I can be of any use, so I looked around
>>> in the WMI implementation in the DSDT and found the following in the
>>> DSTS method:
>>>
>>> [...]
>>> 37486     If ((IIA0 == 0x00120063))
>>> 37487     {
>>> 37488         Local0 = ^^PCI0.LPCB.EC0.DKPS ()
>>> 37489         If ((Local0 == One))
>>> 37490         {
>>> 37491             Return (0x00010001)
>>> 37492         }
>>> 37493         Else
>>> 37494         {
>>> 37495             Return (0x00010000)
>>> 37496         }
>>> 37497     }
>>> [...]
>>>
>>> This is the If statement responsible for the ASUS_WMI_DEVID_KBD_DOCK
>>> device, and it always seems to return 0x00010000 on my machine. I
>>> followed it up the call chain but in the end it just read some bit from
>>> some register of the EC.
>>>
>>> Then I noticed the If statement right above it, which corresponds to
>>> dev_id 0x00060062:
>>>
>>> [...]
>>> 37472     If ((IIA0 == 0x00060062))
>>> 37473     {
>>> 37474         If (^^PCI0.LPCB.EC0.RPIN (0x15))
>>> 37475         {
>>> 37476             Local0 = 0x00010001
>>> 37477         }
>>> 37478         Else
>>> 37479         {
>>> 37480             Local0 = 0x00010000
>>> 37481         }
>>> 37482
>>> 37483         Return (Local0)
>>> 37484     }
>>> [...]
>>>
>>> By a stroke of luck, it turns out it's the correct one! I patched the
>>> driver to query the state on every event and print it out, and it is
>>> exactly what we are looking for.
>>>
>>> The state is 0 if the device is in normal, laptop state and changes to 1
>>> if flipped over 180 degrees. I patched the module so that the
>>> SW_TABLET_MODE switch was set according to it, and everything seems to
>>> be behaving as it should.
>>
>> Good work on figuring this out!
> 
> I'm glad to have learned something new. ACPI was mostly a magic black
> box for me up to now.
> 
>>
>>> This is, of course, not a full solution, as we
>>> still somehow need to decide whether to use the KDB_DOCK device or this
>>> one. I don't know what to do about that. Ideally find some flag in the
>>> ACPI which says which one we should use?
>>>
>>> The event code which is fired when the lid switch state changes, as we
>>> already know from the sparse keymap[1], is 0xfa. When the laptop is
>>> suspended in laptop mode, flipped to tablet mode in its sleep and
>>> awoken, the event is fired. It is, however, not fired when doing it the
>>> other way around, so we should probably check the state on resume as
>>> well.
>>
>> Ok, I've written a patch to try and use the 0x00060062 WMI object/devid
>> first and only if that is not there use the 0x00120063 one which the
>> Bay Trail and Cherry Trail devices use.
> 
> Yeah, that's the solution I had in mind as well and should hopefully be
> fine. Until ASUS ships a device with yet another weird firmware quirk,
> anyway.
> 
>>
>> I've attached the patch, please give it a try.
> 
> I've tested the patch on the laptop applied on top of 5.8.8 and it works
> as it should!

Great, thank you for testing.

> The patch itself looks good to me, but I have one tiny nitpick: A typo
> in my name on line 15. I feel bad for even mentioning that though.

No need to feel bad, I know the feeling, many people mangle
my last name. So I always try to get this right.

So I will fix the mis-spelling of your name and change the:

Reported-by: Samuel Čavoj <samuel@cavoj.net>

to:

Reported-and-tested-by: Samuel Čavoj <samuel@cavoj.net>

And then submit this upstream.

> I'm glad we are able to resolve the issue so quickly. I was going to say
> that the report on bugzilla should be addressed also, but I see you have
> already done that.

Yes, I just hope that the fix works for the model in the
bugzilla too. I expect it will, but you never know.

> Thank you for kindly your work.

You're welcome, thank you for helping me quickly address this
regression.

Regards,

Hans