pinctrl: bcm2835: reduce GPPUD set-up time

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Since the BCM2835 datasheet doesn't exactly specify the set-up time for
the GPIO Pull-up/down Clock Registers there was an assumption of 150 cycles
at a clock rate of 1 MHz. During a discussion [1] in the Raspberry Pi forum
it turns out that clock rate refers to the VPU which has a rate of 250 MHz.
So we can reduce the delay to a sensible value and update the comment above.

I tested this optimization with a Raspberry Pi B and a multimeter.

[1] - https://www.raspberrypi.org/forums/viewtopic.php?f=72&t=163352

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

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Stefan Wahren 2016-10-31 13:21:33 +00:00 • committed by Linus Walleij

parent 684373eaa9

commit b83bd893f3

1 changed files with 6 additions and 4 deletions

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drivers/pinctrl/bcm/pinctrl-bcm2835.c

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