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spi: stm32: add a delay before SPI disable 

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>
Link: https://lore.kernel.org/r/20230906132735.748174-1-valentin.caron@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Valentin Caron 2023-09-06 15:27:35 +02:00 committed by Mark Brown
parent 18495676f7
commit 6de8a70c84
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1 changed files with 8 additions and 0 deletions
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8
drivers/spi/spi-stm32.c
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@ -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)