From: Félix Piédallu <felix.piedallu@non.se.com>
Date: Fri, 6 Jun 2025 13:37:25 +0000 (+0200)
Subject: spi: omap2-mcspi: Disable multi-mode when the previous message kept CS asserted
X-Git-Tag: v6.16-rc2~12^2~2^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=10c24e0d2f7cd2bc8a847cf750f01301ce67dbc8;p=thirdparty%2Fkernel%2Flinux.git

spi: omap2-mcspi: Disable multi-mode when the previous message kept CS asserted

When the last transfer of a SPI message has the cs_change flag, the CS is kept
asserted after the message.
The next message can't use multi-mode because the CS will be briefly deasserted
before the first transfer.

Remove the early exit of the list_for_each_entry because the last transfer
actually needs to be always checked.

Fixes: d153ff4056cb ("spi: omap2-mcspi: Add support for MULTI-mode")
Signed-off-by: Félix Piédallu <felix.piedallu@non.se.com>
Link: https://patch.msgid.link/20250606-cs_change_fix-v1-2-27191a98a2e5@non.se.com
Signed-off-by: Mark Brown <broonie@kernel.org>
---

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index e834fb42fd4b..70bb74b3bd9c 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -134,6 +134,7 @@ struct omap2_mcspi {
 	size_t			max_xfer_len;
 	u32			ref_clk_hz;
 	bool			use_multi_mode;
+	bool			last_msg_kept_cs;
 };
 
 struct omap2_mcspi_cs {
@@ -1269,6 +1270,10 @@ static int omap2_mcspi_prepare_message(struct spi_controller *ctlr,
 	 * multi-mode is applicable.
 	 */
 	mcspi->use_multi_mode = true;
+
+	if (mcspi->last_msg_kept_cs)
+		mcspi->use_multi_mode = false;
+
 	list_for_each_entry(tr, &msg->transfers, transfer_list) {
 		if (!tr->bits_per_word)
 			bits_per_word = msg->spi->bits_per_word;
@@ -1289,22 +1294,17 @@ static int omap2_mcspi_prepare_message(struct spi_controller *ctlr,
 
 		if (list_is_last(&tr->transfer_list, &msg->transfers)) {
 			/* Check if transfer asks to keep the CS status after the whole message */
-			if (tr->cs_change)
+			if (tr->cs_change) {
 				mcspi->use_multi_mode = false;
+				mcspi->last_msg_kept_cs = true;
+			} else {
+				mcspi->last_msg_kept_cs = false;
+			}
 		} else {
 			/* Check if transfer asks to change the CS status after the transfer */
 			if (!tr->cs_change)
 				mcspi->use_multi_mode = false;
 		}
-
-		/*
-		 * If at least one message is not compatible, switch back to single mode
-		 *
-		 * The bits_per_word of certain transfer can be different, but it will have no
-		 * impact on the signal itself.
-		 */
-		if (!mcspi->use_multi_mode)
-			break;
 	}
 
 	omap2_mcspi_set_mode(ctlr);