Re: [RFC PATCH] Add bridge driver to connect sensors to CIO2 device via software nodes on ACPI platforms

From: Dan Scally
Date: Mon Sep 21 2020 - 09:34:03 EST

On 18/09/2020 14:07, Andy Shevchenko wrote:
> On Fri, Sep 18, 2020 at 10:51:57AM +0300, Sakari Ailus wrote:
>> On Thu, Sep 17, 2020 at 03:45:14PM +0300, Andy Shevchenko wrote:
>>> On Thu, Sep 17, 2020 at 11:52:28AM +0100, Dan Scally wrote:
>>>> On 17/09/2020 11:33, Sakari Ailus wrote:
>>>>> a module and not enlarge everyone's kernel, and the initialisation would at
>>>>> the same time take place before the rest of what the CIO2 driver does in
>>>>> probe.
>>>> I thought of that as well, but wasn't sure which was preferable. I can
>>>> compress it into the CIO2 driver though sure.
>>> Sakari, I tend to agree with Dan and have the board file separated from the
>>> driver and even framework.
>> And it'll be linked to the kernel binary then I suppose?
> Solely depends to your Kconfig dependencies and declaration.
> From code perspective you may do it before enumeration of the certain device or
> after with reprobe.
>> I don't have a strong opinion either way, just thought that this will
>> affect anyone using x86 machines, whether or not they have IPU3. I guess it
>> could be compiled in if the ipu3-cio2 driver is enabled?
> Of course!

Apologies both - my inexperience is showing here: I thought you couldn't
make it compile into the kernel where it's dependent on another piece of
code that's configured to be a module? In my case, ipu3-cio2 plus some
other dependencies are configured as modules; VIDEO_DEV and VIDEO_V4L2
notably. Is that not right?

It would probably make the probe() ordering issues easier if it could be
compiled in, since I could just rely on late_initcall() in that case and
I guess that should work.