[PATCH] mtd: spi-nor: Don't let clean_bar() overwrite read/write errors

[Yuho Choi <oss.patchbox@gmail.com>]

With SPI_FLASH_BAR enabled, spi_nor_read() and spi_nor_write() call
clean_bar() at their common exit label and assign its return value to
ret. This is also done on the error paths, so an error from
nor->read(), nor->write() or spi_nor_wait_till_ready() is replaced by
the result of clean_bar(), which is 0 when the bank register is already
0 or was reset successfully. The caller then gets 0 back for a read or
write that did not complete.

Only use the result of clean_bar() when no earlier error occurred, as
was done for spi_nor_erase() in commit a9d9d412e00e ("mtd: spi-nor-core:
Don't overwrite return value if it is non-zero").

Fixes: 8c927809ea96 ("mtd: spi: spi-nor-core: Add back U-Boot specific features")
Signed-off-by: Yuho Choi <oss.patchbox@gmail.com>
---
Tested on sandbox with SPI_FLASH_BAR=y and the emulated m25p16, using
gdb to make spi_nor_read_data() and spi_nor_write_data() return -EIO
after the probe. Without this patch 'sf read' and 'sf write' print OK;
with it they print ERROR -5. 'ut dm spi_flash' and
'ut dm spi_flash_func' pass, and a normal erase/write/read/compare
still works. Not tested on hardware.

 drivers/mtd/spi/spi-nor-core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 937d79af64e..759f511fa20 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -1677,7 +1677,10 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 
 read_err:
 #if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
-	ret = clean_bar(nor);
+	if (ret)
+		clean_bar(nor);
+	else
+		ret = clean_bar(nor);
 #endif
 	return ret;
 }
@@ -2105,7 +2108,10 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 write_err:
 #if CONFIG_IS_ENABLED(SPI_FLASH_BAR)
-	ret = clean_bar(nor);
+	if (ret)
+		clean_bar(nor);
+	else
+		ret = clean_bar(nor);
 #endif
 	return ret;
 }
-- 
2.43.0