hollalinux
/
linux-sg2042
mirror of https://github.com/sophgo/linux-riscv.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

spi: imx: only do necessary changes to ECSPIx_CONFIGREG 

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>
This commit is contained in:
Knut Wohlrab 2016-03-15 14:24:36 +01:00 committed by Mark Brown
parent c508709bcf
commit 793c7f9212
1 changed files with 9 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/spi/spi-imx.c
View File

@ -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;