linux-kernel - Re: lm90 driver no longer working on PCs in 3.13

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Date:	Sun, 26 Jan 2014 20:52:16 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Jean Delvare <khali@...ux-fr.org>,
	LM Sensors <lm-sensors@...sensors.org>,
	linux-kernel@...r.kernel.org, Liam Girdwood <lgirdwood@...il.com>,
	Wei Ni <wni@...dia.com>
Subject: Re: lm90 driver no longer working on PCs in 3.13

On Sun, Jan 26, 2014 at 12:44:38PM -0800, Guenter Roeck wrote:
> On 01/26/2014 12:13 PM, Jean Delvare wrote:

> >Me, I really don't know. I seem to remember I tested Wei's patch set on
> >an emulated ADM1032 chip and it was working fine. So maybe it depends
> >on the kernel configuration, or something changed on the regulator side
> >meanwhile.

> The regulator code changed with 3.13; the dummy regulator no longer exists,
> and the functionality it provided is supposed to be handled automatically.
> But that only really works on devicetree based systems and otherwise returns
> -EPROBE_DEFER as mentioned above.

CONFIG_REGULATOR_DUMMY should never have been used in production, it was
a debug tool to help bringup but it broke things as often as it fixed
them particularly with init ordering which is why it generated a warning
when it was used.  

The dummy driver is still there, if you're doing bringup you can hack it
in still or if you genuniely used it then specify that full constraints
are provided like the changelog says (and as I've previously said).

> Another possible fix would be to have the regulator core return -ENODEV
> instead of -EPROBE_DEFER on non-dt systems. No idea if this would be acceptable
> or even feasible.

No, this would introduce breakage due to init ordering.

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