linux-kernel - Re: [BUG 5/5] [BUG] media: atomisp: atomisp causes touchscreen to stop working on Microsoft Surface 3

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Message-ID: <869d0e2c-b04a-ef35-cfe5-b372c646fce9@redhat.com>
Date:   Mon, 8 Nov 2021 08:55:53 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     Tsuchiya Yuto <kitakar@...il.com>,
        Patrik Gfeller <patrik.gfeller@...il.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Kaixu Xia <kaixuxia@...cent.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Arnd Bergmann <arnd@...db.de>, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [BUG 5/5] [BUG] media: atomisp: atomisp causes touchscreen to
 stop working on Microsoft Surface 3

Hi Mauro,

On 11/8/21 08:41, Mauro Carvalho Chehab wrote:
> Em Mon, 8 Nov 2021 00:39:38 +0100
> Hans de Goede <hdegoede@...hat.com> escreveu:
> 
>> Hi,
>>
>> On 10/21/21 11:52, Tsuchiya Yuto wrote:
>>> Thank you for your comment :-)
>>>
>>> First, I need to correct what I said in the previous mail. I later found
>>> that loading only "atomisp" (as well as its dependency,
>>> atomisp_gmin_platform) does not cause this issue.
>>>
>>> What causes this issue is rather, loading sensor drivers (as well as its
>>> dependency, atomisp_gmin_platform).
>>>
>>> These sensor drivers for surface3 are both not upstream, but I made them
>>> as similar as possible to the upstreamed ones. So, I guess this issue
>>> can still be reproducible on some other devices.  
>>
>> I've run some test on my own surface3 and the problem is the writing
>> of 0x62 (which becomes just 0x02) to the 0x57 register of the PMIC,
>> writing 0x00 to that after loading the sensor driver makes things work
>> again.
>>
>> I have not had time to investigate this further.
>>
>> I used media-staging + your sensor drivers from:
>> https://github.com/kitakar5525/surface3-atomisp-cameras.git
>>
>> Which was enough to figure this out, but I've not actually gotten
>> either of the cameras working :|  I get:
>>
>> [user@...ora nvt]$ ./atomisp-test.sh 
>> p0: OPEN video device `/dev/video2'
> 
> After the patch that moved the output preview to be the first one,
> you should probably use /dev/video0 here:

Thanks for the hint, but I've not rebased my tree to those latest couple
of patches yet, the same tree does work on the T101HA with /dev/video2 :)

I think this may be a module load ordering issue, I believe that the
sensor drivers need to be loaded before the atomisp driver itself
and on the T101HA we are hitting this "sweet spot", where as on
the surface I was loading the not yet merged sensor drivers manually,
causing them to be loaded later.

I still need to verify this theory, Tsuchiya can you perhaps confirm 
that the modules must be loaded in this order?

Regards,

Hans