Messages in this thread | | | Date | Mon, 17 Dec 2012 18:15:19 +0100 | From | Roland Stigge <> | Subject | Re: [PATCH RESEND 0/6 v10] gpio: Add block GPIO |
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On 12/17/2012 05:28 PM, Wolfgang Grandegger wrote: > On 12/17/2012 02:51 PM, Roland Stigge wrote: >> Hi Wolfgang, >>> 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 :(.
From the manual, I read about OWER: "Enables writing PIO_ODSR for the I/O line" (analogous for OWDR). Would interpret this as affecting ODSR (for block GPIO) but not SODR/CODR (as currently with single GPIOs).
Have you tried? ;-)
Thanks in advance,
Roland
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