spi: omap2-mcspi: Disable multi mode when CS should be kept asserted after message

[ Upstream commit a5bf5272295d3f058adeee025d2a0b6625f8ba7b ]

When the last transfer of a SPI message has the cs_change flag, the CS is kept
asserted after the message.
Multi-mode can't respect this as CS is deasserted by the hardware at the end of
the message.

Disable multi-mode when not applicable to the current message.

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-v1-1-27191a98a2e5@non.se.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 532b2e9c31d0d305936126e6043dda667cdd43e7..05766b98de36f775362403edd861f3c9ec6eaf6c 100644 (file)
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -1287,9 +1287,15 @@ static int omap2_mcspi_prepare_message(struct spi_controller *ctlr,
                        mcspi->use_multi_mode = false;
                }
 
-               /* Check if transfer asks to change the CS status after the transfer */
-               if (!tr->cs_change)
-                       mcspi->use_multi_mode = false;
+               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)
+                               mcspi->use_multi_mode = 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