| Message ID | 20191204231931.21378-1-linus.walleij@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | mfd: motorola-cpcap: Do not hardcode SPI mode flags | expand |
Hi Linus, * Linus Walleij <linus.walleij@linaro.org> [700101 00:00]: > The current use of mode flags to us SPI_MODE_0 and > SPI_CS_HIGH is fragile: it overwrites anything already > assigned by the SPI core. Change it thusly: > > - Just |= the SPI_MODE_0 so we keep other flags > - Assign ^= SPI_CS_HIGH since we might be active high > already, and that is usually the case with GPIOs used > for chip select, even if they are in practice active low. > > Add a comment clarifying why ^= SPI_CS_HIGH is the right > choice here. Looks like this breaks booting for droid4 with a cpcap PMIC, probably as regulators won't work. There's no GPIO controller involved in this case for the chip select, the pins are directly controlled by the spi-omap2-mcspi.c driver. From the pin muxing setup we see there's a pull-down on mcspi1_cs0 pin meaning it's active high: /* 0x4a100138 mcspi1_cs0.mcspi1_cs0 ae23 */ OMAP4_IOPAD(0x138, PIN_INPUT_PULLDOWN | MUX_MODE0) My guess a similar issue is with similar patches for all non-gpio spi controllers? Let me know if you want me to test some other changes, or if this patch depends on some other changes. Regards, Tony > Reported-by: Mark Brown <broonie@kernel.org> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > drivers/mfd/motorola-cpcap.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/mfd/motorola-cpcap.c b/drivers/mfd/motorola-cpcap.c > index 52f38e57cdc1..a3bc61b8008c 100644 > --- a/drivers/mfd/motorola-cpcap.c > +++ b/drivers/mfd/motorola-cpcap.c > @@ -279,7 +279,13 @@ static int cpcap_probe(struct spi_device *spi) > spi_set_drvdata(spi, cpcap); > > spi->bits_per_word = 16; > - spi->mode = SPI_MODE_0 | SPI_CS_HIGH; > + spi->mode |= SPI_MODE_0; > + /* > + * Active high should be defined as "inverse polarity" as GPIO-based > + * chip selects can be logically active high but inverted by the GPIO > + * library. > + */ > + spi->mode ^= SPI_CS_HIGH; > > ret = spi_setup(spi); > if (ret) > -- > 2.23.0 >
diff --git a/drivers/mfd/motorola-cpcap.c b/drivers/mfd/motorola-cpcap.c index 52f38e57cdc1..a3bc61b8008c 100644 --- a/drivers/mfd/motorola-cpcap.c +++ b/drivers/mfd/motorola-cpcap.c @@ -279,7 +279,13 @@ static int cpcap_probe(struct spi_device *spi) spi_set_drvdata(spi, cpcap); spi->bits_per_word = 16; - spi->mode = SPI_MODE_0 | SPI_CS_HIGH; + spi->mode |= SPI_MODE_0; + /* + * Active high should be defined as "inverse polarity" as GPIO-based + * chip selects can be logically active high but inverted by the GPIO + * library. + */ + spi->mode ^= SPI_CS_HIGH; ret = spi_setup(spi); if (ret)
The current use of mode flags to us SPI_MODE_0 and SPI_CS_HIGH is fragile: it overwrites anything already assigned by the SPI core. Change it thusly: - Just |= the SPI_MODE_0 so we keep other flags - Assign ^= SPI_CS_HIGH since we might be active high already, and that is usually the case with GPIOs used for chip select, even if they are in practice active low. Add a comment clarifying why ^= SPI_CS_HIGH is the right choice here. Reported-by: Mark Brown <broonie@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- drivers/mfd/motorola-cpcap.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) -- 2.23.0