[PATCH 4.14 58/71] spi: atmel: fix handling of cs_change set on non-last xfer

Greg Kroah-Hartman
2020-01-16T23:33:52Z

From: Mans Rullgard <mans@mansr.com>

commit fed8d8c7a6dc2a76d7764842853d81c770b0788e upstream.

The driver does the wrong thing when cs_change is set on a non-last
xfer in a message. When cs_change is set, the driver deactivates the
CS and leaves it off until a later xfer again has cs_change set whereas
it should be briefly toggling CS off and on again.

This patch brings the behaviour of the driver back in line with the
documentation and common sense. The delay of 10 us is the same as is
used by the default spi_transfer_one_message() function in spi.c.
[gregory: rebased on for-5.5 from spi tree]
Fixes: 8090d6d1a415 ("spi: atmel: Refactor spi-atmel to use SPI framework queue")
Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Link: https://lore.kernel.org/r/20191018153504.4249-1-gregory.clement@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-atmel.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -301,7 +301,6 @@ struct atmel_spi {
bool use_cs_gpios;

bool keep_cs;
- bool cs_active;

u32 fifo_size;
};
@@ -1338,11 +1337,9 @@ static int atmel_spi_one_transfer(struct
&msg->transfers)) {
as->keep_cs = true;
} else {
- as->cs_active = !as->cs_active;
- if (as->cs_active)
- cs_activate(as, msg->spi);
- else
- cs_deactivate(as, msg->spi);
+ cs_deactivate(as, msg->spi);
+ udelay(10);
+ cs_activate(as, msg->spi);
}
}

@@ -1365,7 +1362,6 @@ static int atmel_spi_transfer_one_messag
atmel_spi_lock(as);
cs_activate(as, spi);

- as->cs_active = true;
as->keep_cs = false;

msg->status = 0;