diff mbox series

[2/5] spi: stm32: fix fifo threshold level in case of short transfer

Message ID 1596806485-3810-3-git-send-email-alain.volmat@st.com
State New, archived
Headers show
Series spi: stm32: various driver fixes | expand

Commit Message

Alain Volmat Aug. 7, 2020, 1:21 p.m. UTC
From: Amelie Delaunay <amelie.delaunay@st.com>

When transfer is shorter than half of the fifo, set the data packet size
up to transfer size instead of up to half of the fifo.
Check also that threshold is set at least to 1 data frame.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alain Volmat <alain.volmat@st.com>
---
 drivers/spi/spi-stm32.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

Comments

Mark Brown Aug. 7, 2020, 1:27 p.m. UTC | #1
On Fri, Aug 07, 2020 at 03:21:22PM +0200, Alain Volmat wrote:

> +	/* data_packet should not exceed transfer length */
> +	packet = (half_fifo > xfer_len) ? xfer_len : half_fifo;

Please write normal conditional statements to improve legibility.
diff mbox series

Patch

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 814a3ec3b8ad..005bc16bdf2a 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -467,20 +467,24 @@  static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz,
 /**
  * stm32h7_spi_prepare_fthlv - Determine FIFO threshold level
  * @spi: pointer to the spi controller data structure
+ * @xfer_len: length of the message to be transferred
  */
-static u32 stm32h7_spi_prepare_fthlv(struct stm32_spi *spi)
+static u32 stm32h7_spi_prepare_fthlv(struct stm32_spi *spi, u32 xfer_len)
 {
-	u32 fthlv, half_fifo;
+	u32 fthlv, half_fifo, packet;
 
 	/* data packet should not exceed 1/2 of fifo space */
 	half_fifo = (spi->fifo_size / 2);
 
+	/* data_packet should not exceed transfer length */
+	packet = (half_fifo > xfer_len) ? xfer_len : half_fifo;
+
 	if (spi->cur_bpw <= 8)
-		fthlv = half_fifo;
+		fthlv = packet;
 	else if (spi->cur_bpw <= 16)
-		fthlv = half_fifo / 2;
+		fthlv = packet / 2;
 	else
-		fthlv = half_fifo / 4;
+		fthlv = packet / 4;
 
 	/* align packet size with data registers access */
 	if (spi->cur_bpw > 8)
@@ -488,6 +492,9 @@  static u32 stm32h7_spi_prepare_fthlv(struct stm32_spi *spi)
 	else
 		fthlv -= (fthlv % 4); /* multiple of 4 */
 
+	if (!fthlv)
+		fthlv = 1;
+
 	return fthlv;
 }
 
@@ -1393,7 +1400,7 @@  static void stm32h7_spi_set_bpw(struct stm32_spi *spi)
 	cfg1_setb |= (bpw << STM32H7_SPI_CFG1_DSIZE_SHIFT) &
 		     STM32H7_SPI_CFG1_DSIZE;
 
-	spi->cur_fthlv = stm32h7_spi_prepare_fthlv(spi);
+	spi->cur_fthlv = stm32h7_spi_prepare_fthlv(spi, spi->cur_xferlen);
 	fthlv = spi->cur_fthlv - 1;
 
 	cfg1_clrb |= STM32H7_SPI_CFG1_FTHLV;
@@ -1588,6 +1595,8 @@  static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
 
 	spin_lock_irqsave(&spi->lock, flags);
 
+	spi->cur_xferlen = transfer->len;
+
 	if (spi->cur_bpw != transfer->bits_per_word) {
 		spi->cur_bpw = transfer->bits_per_word;
 		spi->cfg->set_bpw(spi);
@@ -1635,8 +1644,6 @@  static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
 			goto out;
 	}
 
-	spi->cur_xferlen = transfer->len;
-
 	dev_dbg(spi->dev, "transfer communication mode set to %d\n",
 		spi->cur_comm);
 	dev_dbg(spi->dev,