linux-kernel - Re: kernel panic in spi_complete() on spitz (PXA270)

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Message-ID: <4E0CE189.1020000@compulab.co.il>
Date:	Thu, 30 Jun 2011 23:50:17 +0300
From:	Igor Grinberg <grinberg@...pulab.co.il>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Stanislav Brabec <utx@...guin.cz>,
	Marek Vasut <marek.vasut@...il.com>,
	linux-arm-kernel@...ts.infradead.org,
	zaurus-devel@...ts.linuxtogo.org,
	spi-devel-general@...ts.sourceforge.net, vapier@...too.org,
	khilman@...prootsystems.com, dmitry.torokhov@...il.com,
	linux-kernel@...r.kernel.org, pavel@....cz,
	linux-input@...r.kernel.org, eric.y.miao@...il.com,
	akpm@...ux-foundation.org
Subject: Re: kernel panic in spi_complete() on spitz (PXA270)



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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