| From | Sasha Levin <> | Subject | [PATCH 5.12 064/110] i2c: i801: Ensure that SMBHSTSTS_INUSE_STS is cleared when leaving i801_access | Date | Mon, 28 Jun 2021 10:17:42 -0400 |
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From: Heiner Kallweit <hkallweit1@gmail.com>
[ Upstream commit 065b6211a87746e196b56759a70c7851418dd741 ]
As explained in [0] currently we may leave SMBHSTSTS_INUSE_STS set, thus potentially breaking ACPI/BIOS usage of the SMBUS device.
Seems patch [0] needs a little bit more of review effort, therefore I'd suggest to apply a part of it as quick win. Just clearing SMBHSTSTS_INUSE_STS when leaving i801_access() should fix the referenced issue and leaves more time for discussing a more sophisticated locking handling.
[0] https://www.spinics.net/lists/linux-i2c/msg51558.html
Fixes: 01590f361e94 ("i2c: i801: Instantiate SPD EEPROMs automatically") Suggested-by: Hector Martin <marcan@marcan.st> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Reviewed-by: Hector Martin <marcan@marcan.st> Reviewed-by: Jean Delvare <jdelvare@suse.de> Tested-by: Jean Delvare <jdelvare@suse.de> Signed-off-by: Wolfram Sang <wsa@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/i2c/busses/i2c-i801.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c index f9e1c2ceaac0..04a1e38f2a6f 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -978,6 +978,9 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, } out: + /* Unlock the SMBus device for use by BIOS/ACPI */ + outb_p(SMBHSTSTS_INUSE_STS, SMBHSTSTS(priv)); + pm_runtime_mark_last_busy(&priv->pci_dev->dev); pm_runtime_put_autosuspend(&priv->pci_dev->dev); mutex_unlock(&priv->acpi_lock); -- 2.30.2
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