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Joel Stanley d46fddd52d fsi: scom: Fix error handling 
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 f72ddbe1d7 ("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: f72ddbe1d7 ("fsi: scom: Remove retries")
Link: https://lists.ozlabs.org/pipermail/linux-fsi/2021-November/000235.html
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20211207033811.518981-2-joel@jms.id.au
Signed-off-by: Joel Stanley <joel@jms.id.au>
2022-01-31 15:56:55 +10:30
..
cf-fsi-fw.h fsi: cf-fsi-fw: Use the correct style for SPDX License Identifier 2019-06-19 19:35:51 +02:00
fsi-core.c fsi: core: Fix return of error values on failures 2021-06-04 14:11:48 +09:30
fsi-master-aspeed.c fsi: Aspeed: Reduce poll timeout 2021-06-04 15:00:01 +09:30
fsi-master-ast-cf.c fsi: master-ast-cf: Remove redundant error printing in fsi_master_acf_probe() 2021-06-04 15:02:55 +09:30
fsi-master-gpio.c fsi: Add missing MODULE_DEVICE_TABLE 2021-06-04 14:10:45 +09:30
fsi-master-hub.c fsi: master: Constify hub_master_ids 2020-09-10 12:22:50 +09:30
fsi-master.h fsi: master: Add boolean parameter to link_enable function 2020-09-10 12:22:47 +09:30
fsi-occ.c fsi: occ: Store the SBEFIFO FFDC in the user response buffer 2021-10-22 09:54:32 +10:30
fsi-sbefifo.c fsi: sbefifo: Use interruptible mutex locking 2021-10-22 09:54:33 +10:30
fsi-scom.c fsi: scom: Fix error handling 2022-01-31 15:56:55 +10:30
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Makefile fsi: Add ast2600 master driver 2019-11-08 11:28:20 +01:00