Patch "spi: stm32: add a delay before SPI disable" has been added to the 5.15-stable tree

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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 5.15-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-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d9a962a288cc82c1b74386da24905e8f4b70d2c5
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 3c6f201b5dd85..191baa6e45c08 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -268,6 +268,7 @@ 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
@@ -294,6 +295,7 @@ 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;
@@ -454,6 +456,8 @@ 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;
 }
 
@@ -695,6 +699,10 @@ 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_all(spi->dma_tx);
 	if (spi->cur_usedma && spi->dma_rx)



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