[PATCH 2/3] mtd: spi-nor: sst: add missing write_enable

Marco Felsch
2020-09-11T16:55:06Z

According the datasheet [1] the WEL is automatically reset after the
Byte-Program instruction completion. So if we program the device with
byte-size set to 32 and starting from an odd address only the first and
the last byte is written. Fix this by (re-)anble the write support for
the first SPINOR_OP_AAI_WP sequence.

[1] http://ww1.microchip.com/downloads/en/DeviceDoc/20005044C.pdf;
"4.3.2 WRITE ENABLE LATCH (WEL)"

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
drivers/mtd/spi-nor/sst.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/mtd/spi-nor/sst.c b/drivers/mtd/spi-nor/sst.c
index e0af6d25d573..644252e27a2a 100644
--- a/drivers/mtd/spi-nor/sst.c
+++ b/drivers/mtd/spi-nor/sst.c
@@ -79,6 +79,13 @@ static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,

/* Write out most of the data here. */
for (; actual < len - 1; actual += 2) {
+ /* Enable write support if odd address was written before */
+ if (actual == 1) {
+ ret = spi_nor_write_enable(nor);
+ if (ret)
+ goto out;
+ }
+
nor->program_opcode = SPINOR_OP_AAI_WP;

/* write two bytes. */
--
2.20.1