Re: [PATCH 1/4 v2] mfd: add STw481x driver

From: Wolfram Sang
Date: Mon Sep 16 2013 - 11:21:11 EST



On Mon, Sep 16, 2013 at 02:51:18PM +0100, Mark Brown wrote:
> On Mon, Sep 16, 2013 at 02:44:35PM +0200, Linus Walleij wrote:
>
> > I've tried to fix this for DT-only I2C devices
> > and this very driver was the reason.
>
> > But a tiresome regression due to drivers relying on this
> > i2c_device_id not being NULL and inability to remove it from the I2C
> > core without refactoring the world ensued, see:
> > commit c80f52847c50109ca248c22efbf71ff10553dca4
>
> Oh, that was the change...
>
> > Reverted in:
> > commit 661f6c1cd926c6c973e03c6b5151d161f3a666ed
>
> > For this reason I think:
> > http://marc.info/?l=linux-next&m=137148411231784&w=2
>
> > I have tentatively given up getting pure DT I2C drivers
> > to probe, I don't think I have the whole picture, but
> > Wolfram has serious doubts about this and say we have
> > to be careful ....
>
> > Wolfram, do you have some ideas on how we should
> > proceed or ar you happy with merging this as-is?
>
> I'd have expected that it should be possible to change things such that
> the change in the core doesn't produce any change in behaviour for
> existing drivers. Can we not change the patch so that i2c_match_id()
> copes with getting a NULL id_table? Something like this:

I hacked something like this after Linus posted his approach. However, I
found out that run time instanciating ('new_device' file) needs an
id_table. I wasn't to keen on disabling the feature for dt-only drivers.
That's where I stopped, due to lack of time.

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