Re: [PATCH v2] i2c: core: Disable client irq on reboot/shutdown

[Wolfram Sang]

On Fri, Jun 04, 2021 at 04:27:44PM -0700, Stephen Boyd wrote:
> From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> 
> If an i2c client receives an interrupt during reboot or shutdown it may
> be too late to service it by making an i2c transaction on the bus
> because the i2c controller has already been shutdown. This can lead to
> system hangs if the i2c controller tries to make a transfer that is
> doomed to fail because the access to the i2c pins is already shut down,
> or an iommu translation has been torn down so i2c controller register
> access doesn't work.
> 
> Let's simply disable the irq if there isn't a shutdown callback for an
> i2c client when there is an irq associated with the device. This will
> make sure that irqs don't come in later than the time that we can handle
> it. We don't do this if the i2c client device already has a shutdown
> callback because presumably they're doing the right thing and quieting
> the device so irqs don't come in after the shutdown callback returns.
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> [swboyd@xxxxxxxxxxxx: Dropped newline, added commit text, added
> interrupt.h for robot build error]
> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>

I think this is for-current material because it fixes hangs. Or better
for-next to check for side-effects?

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