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

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

[Gregory CLEMENT]

From: Mans Rullgard <mans@mansr.com>

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>
---
Hello,

This patch was first submitted 2 years[1] but was never applied while it
has received the acked-by from Nicolas, and I don't see any review
against it on the mailing list. So I resend it now.

Thanks,

Gregory

[1]: https://lkml.org/lkml/2016/1/17/31

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

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index d88e2aa64839..9e84a93083bc 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -277,7 +277,6 @@ struct atmel_spi {
 	bool			use_pdc;
 
 	bool			keep_cs;
-	bool			cs_active;
 
 	u32			fifo_size;
 	u8			native_cs_free;
@@ -1416,11 +1415,9 @@ static int atmel_spi_one_transfer(struct spi_master *master,
 				 &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);
 		}
 	}
 
@@ -1443,7 +1440,6 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
 	atmel_spi_lock(as);
 	cs_activate(as, spi);
 
-	as->cs_active = true;
 	as->keep_cs = false;
 
 	msg->status = 0;
-- 
2.23.0


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Applied "spi: atmel: fix handling of cs_change set on non-last xfer" to the spi tree

[Mark Brown]

The patch

   spi: atmel: fix handling of cs_change set on non-last xfer

has been applied to the spi tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-5.4

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From fed8d8c7a6dc2a76d7764842853d81c770b0788e Mon Sep 17 00:00:00 2001
From: Mans Rullgard <mans@mansr.com>
Date: Fri, 18 Oct 2019 17:35:04 +0200
Subject: [PATCH] spi: atmel: fix handling of cs_change set on non-last xfer

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

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index acf318e7330c..2f8c79ce05c8 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -302,7 +302,6 @@ struct atmel_spi {
 	bool			use_cs_gpios;
 
 	bool			keep_cs;
-	bool			cs_active;
 
 	u32			fifo_size;
 };
@@ -1376,11 +1375,9 @@ static int atmel_spi_one_transfer(struct spi_master *master,
 				 &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);
 		}
 	}
 
@@ -1403,7 +1400,6 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
 	atmel_spi_lock(as);
 	cs_activate(as, spi);
 
-	as->cs_active = true;
 	as->keep_cs = false;
 
 	msg->status = 0;
-- 
2.20.1


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