This is a note to let you know that I've just added the patch titled fsi: scom: Fix error handling to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fsi-scom-fix-error-handling.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit c4f2c410f02cc7071c7fadb308b3264f22f0d9ed Author: Joel Stanley <joel@xxxxxxxxx> Date: Tue Dec 7 14:08:10 2021 +1030 fsi: scom: Fix error handling [ Upstream commit d46fddd52d11eb6a3a7ed836f9f273e9cf8cd01c ] SCOM error handling is made complex by trying to pass around two bits of information: the function return code, and a status parameter that represents the CFAM error status register. The commit f72ddbe1d7b7 ("fsi: scom: Remove retries") removed the "hidden" retries in the SCOM driver, in preference of allowing the calling code (userspace or driver) to decide how to handle a failed SCOM. However it introduced a bug by attempting to be smart about the return codes that were "errors" and which were ok to fall through to the status register parsing. We get the following errors: - EINVAL or ENXIO, for indirect scoms where the value is invalid - EINVAL, where the size or address is incorrect - EIO or ETIMEOUT, where FSI write failed (aspeed master) - EAGAIN, where the master detected a crc error (GPIO master only) - EBUSY, where the bus is disabled (GPIO master in external mode) In all of these cases we should fail the SCOM read/write and return the error. Thanks to Dan Carpenter for the detailed bug report. Fixes: f72ddbe1d7b7 ("fsi: scom: Remove retries") Link: https://lists.ozlabs.org/pipermail/linux-fsi/2021-November/000235.html Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Signed-off-by: Joel Stanley <joel@xxxxxxxxx> Reviewed-by: Eddie James <eajames@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211207033811.518981-2-joel@xxxxxxxxx Signed-off-by: Joel Stanley <joel@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c index da1486bb6a14..3b427f7e9027 100644 --- a/drivers/fsi/fsi-scom.c +++ b/drivers/fsi/fsi-scom.c @@ -289,7 +289,7 @@ static int put_scom(struct scom_device *scom, uint64_t value, int rc; rc = raw_put_scom(scom, value, addr, &status); - if (rc == -ENODEV) + if (rc) return rc; rc = handle_fsi2pib_status(scom, status); @@ -308,7 +308,7 @@ static int get_scom(struct scom_device *scom, uint64_t *value, int rc; rc = raw_get_scom(scom, value, addr, &status); - if (rc == -ENODEV) + if (rc) return rc; rc = handle_fsi2pib_status(scom, status);