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nyan: Switch USB VBUS GPIOs from outputs to pulled-up inputs

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The USB VBUS GPIOs on Nyan boards are two-directional: usually the SoC
sets them high or low to enable USB power, but on overcurrent conditions
they get forcefully driven low by the voltage source. To avoid driving
it from two sides, we configure them on the SoC side as tristated input
pins with a pull-up instead.

BUG=None
TEST=Made sure USB devices still get detected.

Change-Id: I423cb312805cbacb651a569ddc1530813b148576
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/178914
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Tom Warren <twarren@nvidia.com>
This commit is contained in:
Julius Werner 2013-12-05 11:03:37 -08:00 • committed by chrome-internal-fetch
commit e47b6a609b
1 changed files with 4 additions and 4 deletions
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8
src/mainboard/google/nyan/mainboard.c
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@ -180,10 +180,10 @@ static void setup_pinmux(void)
pinmux_set_config(PINMUX_SDMMC4_DAT7_INDEX,
PINMUX_SDMMC4_DAT7_FUNC_SDMMC4 | pin_up);
/* TODO: This is supposed to work with the USB special function pinmux,
* but it doesn't. Go with GPIOs for now and solve the problem later. */
gpio_output_open_drain(GPIO(N4), 1); /* USB VBUS EN0 */
gpio_output_open_drain(GPIO(N5), 1); /* USB VBUS EN1 */
/* We pull the USB VBUS signals up but keep them as inputs since the
* voltage source likes to drive them low on overcurrent conditions */
gpio_input_pullup(GPIO(N4)); /* USB VBUS EN0 */
gpio_input_pullup(GPIO(N5)); /* USB VBUS EN1 */
/* Clock output 1 (for external peripheral) */
pinmux_set_config(PINMUX_DAP_MCLK1_INDEX,