On 12/17/2012 02:51 PM, Roland Stigge wrote: > Hi Wolfgang, > > On 12/17/2012 02:32 PM, Roland Stigge wrote: >> And I guess Russell is right: If possible, we should write outputs >> simultaneously via ODSR (plus OWER/OWDR/OWSR) instead of separate set/clear. >> >> I wonder if we need to save/restore the state of OWSR at every write >> operation or if we need/can cache it. Assuming that block GPIO are the >> only code in the kernel that manipulates ODSR. > > Can you please test the following: > > +static void at91_gpiolib_set_block(struct gpio_chip *chip, unsigned long > mask, unsigned long val) > +{ > + struct at91_gpio_chip *at91_gpio = to_at91_gpio_chip(chip); > + void __iomem *pio = at91_gpio->regbase; > + > + __raw_writel(~mask, pio + PIO_OWDR);
This would also disable normal GPIOs configured for output! From the manual I understand that if the pin is configured for output, we could either use PIO_SODR/PIO_CODR to set/clear the bits individually or PIO_ODSR for synchronous data output. But than we need to care about the non-block GPIO outputs as well... requiring a read-modify-write cycle :(. Wolfgang. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/