From: broonie@opensource•wolfsonmicro.com (Mark Brown)
To: linux-arm-kernel@lists•infradead.org
Subject: Device probe order (i2c regulator vs. platform device)
Date: Wed, 24 Mar 2010 10:21:44 +0000 [thread overview]
Message-ID: <20100324102144.GA21935@rakim.wolfsonmicro.main> (raw)
In-Reply-To: <E4D3F24EA6C9E54F817833EAE0D912AC09C80E05C7@bssrvexch01.BS.local>
On Wed, Mar 24, 2010 at 08:10:38AM +0100, Marek Szyprowski wrote:
[Reflowed into 80 columns - please fix your mail client to wrap text, it
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> I've encountered a problem with regulator framework and the device
> probe order. In my system there is a pmic chip connected thought i2c bus
> and a platform device (let's call it A) that depends on the regulator
> device (for proper probing pmic chip must enable voltage to the device
> A). In the current configuration the i2c driver is also a platform
> device. However during the system initialization the device A is probed
> before the i2c driver would register pmic chip and its regulators.
This is (if I'm parsing what you say above correctly) a very common case
- if you look at most of the existing PMIC core and regulator drivers
you'll see that their initcalls are subsys_initcall(), and similarly for
the I2C controller drivers they use. This means that at boot the PMICs
come up before pretty much any other device.
> How I can delay probing the device A to the moment when the regulator
> device will be available in the system? Is there any generic was of
> changing the device probe order?
The solution above is the other way around - it ensures that the
regulators come up first - but achieves the same effect. Unfortunately
it's not as generic as would be best but it resolves the issues.
next prev parent reply other threads:[~2010-03-24 10:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-24 7:10 Device probe order (i2c regulator vs. platform device) Marek Szyprowski
2010-03-24 9:19 ` Andy Green
2010-03-24 11:11 ` Marek Szyprowski
2010-03-24 12:50 ` Andy Green
2010-03-24 13:11 ` Mark Brown
2010-03-24 13:22 ` Andy Green
2010-03-24 11:32 ` Mark Brown
2010-03-24 12:11 ` Andy Green
2010-03-24 14:01 ` Mark Brown
2010-03-24 14:38 ` Andy Green
2010-03-25 10:22 ` Mark Brown
2010-03-25 10:52 ` Andy Green
2010-03-24 10:21 ` Mark Brown [this message]
2010-03-24 10:57 ` Andy Green
2010-03-24 11:02 ` Marek Szyprowski
2010-03-24 11:08 ` Mark Brown
2010-03-24 11:27 ` Andy Green
2010-03-24 12:19 ` Mark Brown
2010-03-24 12:29 ` Andy Green
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