Messages in this thread |  | | From | Linus Walleij <> | Date | Tue, 7 Jan 2020 10:57:10 +0100 | Subject | Re: [PATCH] mfd: motorola-cpcap: Do not hardcode SPI mode flags |
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On Thu, Dec 19, 2019 at 6:04 PM Tony Lindgren <tony@atomide.com> wrote:
> * 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.
So this must mean that something else is setting SPI_CS_HIGH for this driver, such as the device tree, right?
And the |= SPI_CS_HIGH assignment in the driver is just surplus and we should just delete this code instead.
Would that be right?
Yours, Linus Walleij
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