linux-kernel - Re: da9030: ldo11 ignores disable

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Date:	Tue, 14 Jul 2009 15:34:35 +0000
From:	Jonathan Cameron <jic23@....ac.uk>
To:	Eric Miao <eric.y.miao@...il.com>
CC:	Liam Girdwood <lrg@...mlogic.co.uk>,
	LKML <linux-kernel@...r.kernel.org>,
	Mark Brown <broonie@...ena.org.uk>, mike.rapoport@...il.com,
	Paul Shen <bshen9@...vell.com>,
	Haojian Zhuang <hzhuang1@...vell.com>
Subject: Re: da9030: ldo11 ignores disable

Eric Miao wrote:
> Eric Miao wrote:
>> Jonathan Cameron wrote:
>>> Liam Girdwood wrote:
>>>> On Thu, 2009-06-25 at 15:39 +0000, Jonathan Cameron wrote:
>>>>> Hi All,
>>>>>
>>>>> Whilst testing a regulator machine config I've run into a weird issue.
>>>>>
>>>>> The preliminary data sheet I have suggests that there are two enable
>>>>> registers
>>>>> for ldo11 but neither rctl22 or rctl11 seems to have any effect (on
>>>>> their own
>>>>> or both cleared together). I can change the voltage just fine, but not
>>>>> actually turn it off.
>>>>>
>>>>> Anyone come across this problem or have any idea what is going on?
>>>> I've come across something similar in the past with two enable bits
>>>> causing I2C register cache coherency issues. The cache bits became out
>>>> of sync with reality and stopped some I2C writes happening.
>>> Don't thing that could happen here.
>>>> Another option is that your hardware config doesn't allow ldo11 to be
>>>> disabled ?
>>> Other than the obvious possibility that the hardware has a bug, I can't
>>> seem to find a reason why this shouldn't work.
>>>
>> I didn't meet this problem, Haojian & Paul, ever had this problem before?
>> Or try lookup the Errata for the Arava chip.
> 
> Hi Jonathan,
> 
> Here's a hint, check register 0x1b - which looks suspicious to me to have
> some side effects to LDO11.
> 
Thanks Eric,

I'll have a play and see if this reg (start up control) effects the ability
to turn it off at other points.

Jonathan
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