diff mbox series

spi: stm32: add a delay before SPI disable

Message ID 20230906132735.748174-1-valentin.caron@foss.st.com
State Accepted
Commit 6de8a70c84ee0586fdde4e671626b9caca6aed74
Headers show
Series spi: stm32: add a delay before SPI disable | expand

Commit Message

Valentin Caron Sept. 6, 2023, 1:27 p.m. UTC
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@foss.st.com>
---
 drivers/spi/spi-stm32.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Mark Brown Sept. 12, 2023, 11:38 a.m. UTC | #1
On Wed, 06 Sep 2023 15:27:35 +0200, Valentin Caron wrote:
> 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.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: stm32: add a delay before SPI disable
      commit: 6de8a70c84ee0586fdde4e671626b9caca6aed74

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark
diff mbox series

Patch

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index b6d66caba4c0..ef665f470c5b 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -277,6 +277,7 @@  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
@@ -304,6 +305,7 @@  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;
@@ -468,6 +470,8 @@  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;
 }
 
@@ -709,6 +713,10 @@  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)