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

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Message-Id: <20210604212752.3547301-1-swboyd@chromium.org>
Date:   Fri,  4 Jun 2021 14:27:52 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Wolfram Sang <wsa@...nel.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: [PATCH] i2c: core: Disable client irq on reboot/shutdown

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>
[swboyd@...omium.org: Dropped newline, added commit text]
Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---

Dmitry, please add Signed-off-by

This supersedes https://lore.kernel.org/r/20210510220012.2003285-1-swboyd@chromium.org

 drivers/i2c/i2c-core-base.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 5a97e4a02fa2..7ea5d7cc5974 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -627,6 +627,8 @@ 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