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

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Message-ID: <YLwAo2L7n0IJ+Q3/@google.com>
Date:   Sat, 5 Jun 2021 15:54:27 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Wolfram Sang <wsa@...nel.org>, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2] i2c: core: Disable client irq on reboot/shutdown

On Fri, Jun 04, 2021 at 04:27:44PM -0700, Stephen Boyd wrote:
> From: Dmitry Torokhov <dmitry.torokhov@...il.com>
> 
> 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@...il.com>
> Reported-by: kernel test robot <lkp@...el.com>
> [swboyd@...omium.org: Dropped newline, added commit text, added
> interrupt.h for robot build error]
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

> ---
> 
> Dmitry, please add Signed-off-by so this can be merged through i2c
> 
> This supersedes https://lore.kernel.org/r/20210510220012.2003285-1-swboyd@chromium.org
> 
> Changes from v1 (https://lore.kernel.org/r/20210604212752.3547301-1-swboyd@chromium.org)
>  * Add interrupt.h include for robot
> 
>  drivers/i2c/i2c-core-base.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 5a97e4a02fa2..e314ccaf114a 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -24,6 +24,7 @@
>  #include <linux/i2c-smbus.h>
>  #include <linux/idr.h>
>  #include <linux/init.h>
> +#include <linux/interrupt.h>
>  #include <linux/irqflags.h>
>  #include <linux/jump_label.h>
>  #include <linux/kernel.h>
> @@ -627,6 +628,8 @@ static void i2c_device_shutdown(struct device *dev)
>  	driver = to_i2c_driver(dev->driver);
>  	if (driver->shutdown)
>  		driver->shutdown(client);
> +	else if (client->irq > 0)
> +		disable_irq(client->irq);
>  }
>  
>  static void i2c_client_dev_release(struct device *dev)
> 
> base-commit: 8124c8a6b35386f73523d27eacb71b5364a68c4c
> -- 
> https://chromeos.dev
> 

-- 
Dmitry