diff options
| author | Valentin Caron <valentin.caron@foss.st.com> | 2023-09-06 16:27:35 +0300 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2023-09-11 03:24:00 +0300 |
| commit | 6de8a70c84ee0586fdde4e671626b9caca6aed74 (patch) | |
| tree | 483995488b72c8d00f42b51f5a2266bbe9a603d6 /drivers/spi | |
| parent | 18495676f7886e105133f1dc06c1d5e8d5436f32 (diff) | |
| download | linux-6de8a70c84ee0586fdde4e671626b9caca6aed74.tar.xz | |
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>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-stm32.c | 8 |
1 files changed, 8 insertions, 0 deletions
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) |