linux-kernel - [RFC PATCH 2/4] spi: spi-fsl-spi: relax message sanity checking a little

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Date:   Wed, 27 Mar 2019 14:30:51 +0000
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Mark Brown <broonie@...nel.org>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Fabio Estevam <festevam@...il.com>,
        Rasmus Villemoes <Rasmus.Villemoes@...vas.se>
Subject: [RFC PATCH 2/4] spi: spi-fsl-spi: relax message sanity checking a
 little

The comment says that we should not allow changes (to
bits_per_word/speed_hz) while CS is active, and indeed the code below
does fsl_spi_setup_transfer() when the ->cs_change of the previous
spi_transfer was set (and for the very first transfer).

So the sanity checking is a bit too strict - we can change it to
follow the same logic as is used by the actual transfer loop.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
---
 drivers/spi/spi-fsl-spi.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsl-spi.c b/drivers/spi/spi-fsl-spi.c
index 6d114daa178a..481b075689b5 100644
--- a/drivers/spi/spi-fsl-spi.c
+++ b/drivers/spi/spi-fsl-spi.c
@@ -370,13 +370,15 @@ static int fsl_spi_do_one_msg(struct spi_master *master,
 	int status;
 
 	/* Don't allow changes if CS is active */
-	first = list_first_entry(&m->transfers, struct spi_transfer,
-			transfer_list);
+	cs_change = 1;
 	list_for_each_entry(t, &m->transfers, transfer_list) {
+		if (cs_change)
+			first = t;
+		cs_change = t->cs_change;
 		if ((first->bits_per_word != t->bits_per_word) ||
 			(first->speed_hz != t->speed_hz)) {
 			dev_err(&spi->dev,
-				"bits_per_word/speed_hz should be same for the same SPI transfer\n");
+				"bits_per_word/speed_hz cannot change while CS is active\n");
 			return -EINVAL;
 		}
 	}
-- 
2.20.1