* Linus Walleij <linus.walleij@xxxxxxxxxx> [200107 09:58]: > On Thu, Dec 19, 2019 at 6:04 PM Tony Lindgren <tony@xxxxxxxxxxx> wrote: > > > * Linus Walleij <linus.walleij@xxxxxxxxxx> [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. > > So this must mean that something else is setting SPI_CS_HIGH > for this driver, such as the device tree, right? Hmm yes we have "spi-cs-high" property set in the dts. But looking at drivers/spi/spi-omap2-mcspi.c, it also provides an option to use a GPIO for chip select in omap2_mcspi_setup(). That does not seem to be used though based on a quick grep though. > And the |= SPI_CS_HIGH assignment in the driver is just > surplus and we should just delete this code instead. > > Would that be right? Sorry I don't know, maybe. If you have some test patch to try I can easily test. Regards, Tony
