spi: imx: only do necessary changes to ECSPIx_CONFIGREG (793c7f92) · Commits · 戴 / test

If the SPI chip select (CS) for a dedicated channel is done manually by the used higher device driver, the CS may be active while writing to ECSPIx_CONFIGREG. To prevent unwanted clock edges when selecting the clock mode, only do the necessary changes to the i.MX SPI configuration register and leave not selected channels untouched. To prevent unwanted clock edges on first use, an empty dummy transmission shall be done by the initialization procedure of the device driver of this channel. This will set the clock mode to the correct state. Signed-off-by:

Knut Wohlrab <knut.wohlrab@de.bosch.com> Signed-off-by:

Dirk Behme <dirk.behme@de.bosch.com> Acked-by:

Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by:

Mark Brown <broonie@kernel.org>

drivers/spi/spi-imx.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -333,8 +333,9 @@ static void __maybe_unused mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
		static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
		struct spi_imx_config *config)
		{
		u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0;
		u32 ctrl = MX51_ECSPI_CTRL_ENABLE;
		u32 clk = config->speed_hz, delay, reg;
		u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);

		/*
		* The hardware seems to have a race condition when changing modes. The
		@@ -358,13 +359,20 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,

		if (config->mode & SPI_CPHA)
		cfg \|= MX51_ECSPI_CONFIG_SCLKPHA(config->cs);
		else
		cfg &= ~MX51_ECSPI_CONFIG_SCLKPHA(config->cs);

		if (config->mode & SPI_CPOL) {
		cfg \|= MX51_ECSPI_CONFIG_SCLKPOL(config->cs);
		cfg \|= MX51_ECSPI_CONFIG_SCLKCTL(config->cs);
		} else {
		cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(config->cs);
		cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(config->cs);
		}
		if (config->mode & SPI_CS_HIGH)
		cfg \|= MX51_ECSPI_CONFIG_SSBPOL(config->cs);
		else
		cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(config->cs);

		if (spi_imx->usedma)
		ctrl \|= MX51_ECSPI_CTRL_SMC;

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