Merge tag 'spi-fix-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi

Pull spi fix from Mark Brown:
 "One driver specific change here which handles the case where a SPI
  device for some reason tries to change the bus speed during a message
  on fsl_spi hardware, this should be very unusual"

* tag 'spi-fix-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: fsl_spi: Don't change speed while chipselect is active

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/spi/spi-fsl-spi.c b/drivers/spi/spi-fsl-spi.c
index 731624f157fc..93152144fd2e 100644
--- a/drivers/spi/spi-fsl-spi.c
+++ b/drivers/spi/spi-fsl-spi.c
@@ -333,13 +333,26 @@ static int fsl_spi_prepare_message(struct spi_controller *ctlr,
 {
 	struct mpc8xxx_spi *mpc8xxx_spi = spi_controller_get_devdata(ctlr);
 	struct spi_transfer *t;
+	struct spi_transfer *first;
+
+	first = list_first_entry(&m->transfers, struct spi_transfer,
+				 transfer_list);
 
 	/*
 	 * In CPU mode, optimize large byte transfers to use larger
 	 * bits_per_word values to reduce number of interrupts taken.
+	 *
+	 * Some glitches can appear on the SPI clock when the mode changes.
+	 * Check that there is no speed change during the transfer and set it up
+	 * now to change the mode without having a chip-select asserted.
 	 */
-	if (!(mpc8xxx_spi->flags & SPI_CPM_MODE)) {
-		list_for_each_entry(t, &m->transfers, transfer_list) {
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		if (t->speed_hz != first->speed_hz) {
+			dev_err(&m->spi->dev,
+				"speed_hz cannot change during message.\n");
+			return -EINVAL;
+		}
+		if (!(mpc8xxx_spi->flags & SPI_CPM_MODE)) {
 			if (t->len < 256 || t->bits_per_word != 8)
 				continue;
 			if ((t->len & 3) == 0)
@@ -348,7 +361,7 @@ static int fsl_spi_prepare_message(struct spi_controller *ctlr,
 				t->bits_per_word = 16;
 		}
 	}
-	return 0;
+	return fsl_spi_setup_transfer(m->spi, first);
 }
 
 static int fsl_spi_transfer_one(struct spi_controller *controller,