From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org, Eric Miao <eric.y.miao@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Grant Likely <grant.likely@linaro.org>
Subject: Re: [PATCH 2/2] spi/pxa2xx: use a flag to check if the device is runtime suspended
Date: Wed, 19 Jun 2013 10:44:37 +0300 [thread overview]
Message-ID: <20130619074437.GF11878@intel.com> (raw)
In-Reply-To: <20130618180948.GP1403@sirena.org.uk>
On Tue, Jun 18, 2013 at 07:09:48PM +0100, Mark Brown wrote:
> On Tue, Jun 18, 2013 at 05:29:45PM +0300, Mika Westerberg wrote:
> > Current code calls pm_runtime_suspended() in the interrupt handler to check
> > if the device is suspended or not. However, runtime PM status of the device
> > is only set to suspended once all PM runtime suspend hooks have executed.
>
> > In our case we have the device bound to the ACPI power domain and its
> > runtime suspend hook will put the device to D3hot (or D3cold if possible).
> > This effectively means that the device is powered off before its state is
> > set to runtime suspended. During this time, it might get an interrupt that
> > is meant for another device (as the interrupt line is shared), and because
> > the device is powered off accessing its registers will return 0xffffffff
> > that the driver misinterprets as an invalid state. When this happens user
> > will see messages like below on the console:
>
> This sounds like a problem which will affect a lot of devices and hence
> ought to be handled better by the PM core or at least frameworks in
> general. Is it really device specific?
No, it's not device specific. However, I've seen it only happen with the
SPI controller on Lynxpoint.
I agree that it is better handled outside of the driver (or provide some
API for drivers). One thing that immediately came to mind is
adding pm_runtime_suspending() that could be used here like:
ssp_int()
{
if (pm_runtime_suspending(dev) || pm_runtime_suspending(dev))
return IRQ_NONE;
...
or something like that?
next prev parent reply other threads:[~2013-06-19 7:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-18 14:29 [PATCH 1/2] spi/pxa2xx: use GFP_ATOMIC in sg table allocation Mika Westerberg
2013-06-18 14:29 ` [PATCH 2/2] spi/pxa2xx: use a flag to check if the device is runtime suspended Mika Westerberg
2013-06-18 18:09 ` Mark Brown
2013-06-19 7:44 ` Mika Westerberg [this message]
2013-06-19 9:23 ` Mark Brown
2013-06-19 9:25 ` Russell King - ARM Linux
2013-06-19 9:39 ` Mark Brown
2013-06-19 10:05 ` Russell King - ARM Linux
2013-06-19 11:02 ` Mika Westerberg
2013-06-19 13:59 ` Mark Brown
2013-06-18 18:11 ` [PATCH 1/2] spi/pxa2xx: use GFP_ATOMIC in sg table allocation Mark Brown
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