Message-ID: <4E0CE189.1020000@compulab.co.il>
Date: Thu, 30 Jun 2011 23:50:17 +0300
From: Igor Grinberg <grinberg@compulab.co.il>
Organization: CompuLab Ltd.
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To: Mark Brown <broonie@opensource.wolfsonmicro.com>
CC: Stanislav Brabec <utx@penguin.cz>, Marek Vasut <marek.vasut@gmail.com>,
        linux-arm-kernel@lists.infradead.org, zaurus-devel@www.linuxtogo.org,
        spi-devel-general@lists.sourceforge.net, vapier@gentoo.org,
        khilman@deeprootsystems.com, dmitry.torokhov@gmail.com,
        linux-kernel@vger.kernel.org, pavel@ucw.cz,
        linux-input@vger.kernel.org, eric.y.miao@gmail.com,
        akpm@linux-foundation.org
Subject: Re: kernel panic in spi_complete() on spitz (PXA270)
References: <1308845380.4533.54.camel@oct.suse.cz> <201106301352.21684.marek.vasut@gmail.com> <1309445118.4406.47.camel@oct.suse.cz> <4E0C957F.8080807@compulab.co.il> <1309450406.4406.59.camel@oct.suse.cz> <4E0CB518.2080703@compulab.co.il> <20110630180105.GA5064@opensource.wolfsonmicro.com>
In-Reply-To: <20110630180105.GA5064@opensource.wolfsonmicro.com>
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On 06/30/11 21:01, Mark Brown wrote:
> On Thu, Jun 30, 2011 at 08:40:40PM +0300, Igor Grinberg wrote:
>> On 06/30/11 19:13, Stanislav Brabec wrote:
>
>>>  I seen two
>>> proposals:
>>> - As ADS7846 hardware does not require dedicated regulator, don't
>>>   require it in driver and fail only on platforms that have a dedicated
>>>   regulator.
>> The thing is that ads7846 chip itself just requires power supply
> Right, and the regulator API hides the non-switchability of the supply
> from the driver so there's no need for the driver to worry about how the
> supplies are wired up.  It just turns the regulator on when it needs it
> and turns it off when it doesn't.
>
>>>> 1) add regulator definition for ads7846 into the board file
>>> There is no dedicated regulator on spitz, ADS7846 uses common always-on
>>> power supply.
>> Is there a kind of regulator for this case (except dummy)?
>> Some kind of fixed regulator which is not binded to any supply?
> This is just a fixed voltage regulator, support for that has been in the
> kernel since the regulator API was merged.  This is the best solution,
> it ensures that you don't mistakenly activate dummy reglators for
> supplies that really need software control.

Right, just as I thought (I still haven't made myself familiar with all the
regulator API aspects).

Stanislav,
Can't you define a fixed voltage regulator for the ads7846 in spitz board file?
This shouldn't be a hard task and is the right solution from the regulator API POV.


-- 
Regards,
Igor.

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