Re: [PATCH] media: ipu3: add a module to probe sensors via ACPI

From: Jordan Hand <jorhand@linux.microsoft.com>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Linux Media Mailing List <linux-media@vger.kernel.org>,
	Bingbu Cao <bingbu.cao@intel.com>,
	Tian Shu Qiu <tian.shu.qiu@intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"open list:STAGING SUBSYSTEM" <devel@driverdev.osuosl.org>
Subject: Re: [PATCH] media: ipu3: add a module to probe sensors via ACPI
Date: Tue, 30 Jun 2020 18:16:47 -0700	[thread overview]
Message-ID: <6c24193c-0ba4-7c6e-1711-8221ee133826@linux.microsoft.com> (raw)
In-Reply-To: <20200526143110.GC3284396@kuha.fi.intel.com>

On 5/26/20 7:31 AM, Heikki Krogerus wrote:
> On Fri, May 22, 2020 at 11:57:36AM +0200, Mauro Carvalho Chehab wrote:
>> Em Thu, 21 May 2020 11:00:19 +0300
>> Andy Shevchenko <andy.shevchenko@gmail.com> escreveu:
>>
>>> +Cc: Heikki (swnode expert)
>>>
>>> On Wed, May 20, 2020 at 2:19 PM Mauro Carvalho Chehab
>>> <mchehab+huawei@kernel.org> wrote:
>>>> Em Wed, 20 May 2020 11:26:08 +0300
>>>> Sakari Ailus <sakari.ailus@linux.intel.com> escreveu:
>>>
>>> ...
>>>
>>>> As I said, the problem is not probing the sensor via ACPI, but, instead,
>>>> to be able receive platform-specific data.
>>>
>>> There is no problem with swnodes, except missing parts (*).
>>> I have Skylake laptop with IPU3 and with half-baked ACPI tables, but
>>> since we have drivers in place with fwnode support, we only need to
>>> recreate fwnode graph in some board file to compensate the gap in
>>> ACPI.
>>>
>>> *) Missing part is graph support for swnodes. With that done it will
>>> be feasible to achieve the rest.
>>> I forgot if we have anything for this already done. Heikki?
>>
>> Hmm... I guess I should try this approach. I never heard about swnodes
>> before. Do you have already some patch with the needed swnodes setup,
>> and the missing parts to recreate the fwnode graph?
> 
> Here you go.
> 

For anyone interested, I have taken Heikki's patch and attempted to use 
swnodes to patch the incomplete dsdt on my laptop to use with ipu3; the 
code is currently in a github repo[1].

In particular, patches 1, 2, and 3 setup the software_node 
infrastructure. Patch 5 shows how we might use software nodes where ACPI 
fails.

My sensor driver (in patch 4) doesn't actually work right now which is 
why I haven't brought any of this to the mailing list yet, but that's 
another story :)

I would just submit a patchset, but since my sensor driver doesn't work, 
I can't gully test the rest of it. But if someone has a system where the 
drivers in question are upstream and work, something like this could be 
a good path forward.

- Jordan

[1] https://github.com/jhand2/surface-camera/tree/master/patches