This is a note to let you know that I've just added the patch titled
spi: stm32: add a delay before SPI disable
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
spi-stm32-add-a-delay-before-spi-disable.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1376fd36d5c00ea9db90b275f3f8ac38274f4079
Author: Valentin Caron <valentin.caron@xxxxxxxxxxx>
Date: Wed Sep 6 15:27:35 2023 +0200
spi: stm32: add a delay before SPI disable
[ Upstream commit 6de8a70c84ee0586fdde4e671626b9caca6aed74 ]
As explained in errata sheet, in section "2.14.5 Truncation of SPI output
signals after EOT event":
On STM32MP1x, EOT interrupt can be thrown before the true end of
communication.
So we add a delay of a half period to wait the real end of the
transmission.
Link: https://www.st.com/resource/en/errata_sheet/es0539-stm32mp131x3x5x-device-errata-stmicroelectronics.pdf
Signed-off-by: Valentin Caron <valentin.caron@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230906132735.748174-1-valentin.caron@xxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 7ddf9db776b06..4737a36e5d4e9 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -275,6 +275,7 @@ struct stm32_spi_cfg {
* @fifo_size: size of the embedded fifo in bytes
* @cur_midi: master inter-data idleness in ns
* @cur_speed: speed configured in Hz
+ * @cur_half_period: time of a half bit in us
* @cur_bpw: number of bits in a single SPI data frame
* @cur_fthlv: fifo threshold level (data frames in a single data packet)
* @cur_comm: SPI communication mode
@@ -302,6 +303,7 @@ struct stm32_spi {
unsigned int cur_midi;
unsigned int cur_speed;
+ unsigned int cur_half_period;
unsigned int cur_bpw;
unsigned int cur_fthlv;
unsigned int cur_comm;
@@ -466,6 +468,8 @@ static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz,
spi->cur_speed = spi->clk_rate / (1 << mbrdiv);
+ spi->cur_half_period = DIV_ROUND_CLOSEST(USEC_PER_SEC, 2 * spi->cur_speed);
+
return mbrdiv - 1;
}
@@ -707,6 +711,10 @@ static void stm32h7_spi_disable(struct stm32_spi *spi)
return;
}
+ /* Add a delay to make sure that transmission is ended. */
+ if (spi->cur_half_period)
+ udelay(spi->cur_half_period);
+
if (spi->cur_usedma && spi->dma_tx)
dmaengine_terminate_async(spi->dma_tx);
if (spi->cur_usedma && spi->dma_rx)
