diff options
| author | Randall Spangler <rspangler@chromium.org> | 2012-05-10 14:52:20 -0700 |
|---|---|---|
| committer | Randall Spangler <rspangler@chromium.org> | 2012-05-10 15:17:01 -0700 |
| commit | f28f2b2e518d50001b03aeffac747e2f17d2917f (patch) | |
| tree | c5c542d4cfe2663d5b5d87eb1ae3d1c5c2f7f64d /chip/lm4/gpio.c | |
| parent | 8d48971e917b22a98adab4e6c64fdca667b21e26 (diff) | |
| download | chrome-ec-f28f2b2e518d50001b03aeffac747e2f17d2917f.tar.gz | |
Use open drain reset signals, and clean up signals to 5VALW-powered devices
Open drain cleanup minimizes leakage and signal glitching on shared
reset/signal lines, and is tidier than explicitly switching the
signals between inputs/outputs.
Touchscreen and lightbar are powered by +5VALW so their signals need
to be dropped when +5VALW is off to avoid leakage, and so they see a
clean reset signal when they're powered up.
Moved +5VALW power-on to S5-S3 transition, to minimize power draw in
S5. This also ensures that 5VALW-powered devices get reset when the
device bounces through S5. (No effect on proto1, where 5VALW is not
under EC control.)
Signed-off-by: Randall Spangler <rspangler@chromium.org>
BUG=chrome-os-partner:9172
TEST=boot and shutdown system; still works.
Change-Id: Ia4bf0703292a189c324ce283d1e79a33776ee40f
Diffstat (limited to 'chip/lm4/gpio.c')
| -rw-r--r-- | chip/lm4/gpio.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/chip/lm4/gpio.c b/chip/lm4/gpio.c index 54ab546f00..cb08533413 100644 --- a/chip/lm4/gpio.c +++ b/chip/lm4/gpio.c @@ -184,14 +184,18 @@ int gpio_set_flags(enum gpio_signal signal, int flags) if (flags & GPIO_OUTPUT) { /* Output */ - LM4_GPIO_DIR(g->port) |= g->mask; - + /* Select open drain first, so that we don't glitch the signal + * when changing the line to an output. */ if (g->flags & GPIO_OPEN_DRAIN) LM4_GPIO_ODR(g->port) |= g->mask; else LM4_GPIO_ODR(g->port) &= ~g->mask; + + LM4_GPIO_DIR(g->port) |= g->mask; } else { /* Input */ + LM4_GPIO_DIR(g->port) &= ~g->mask; + if (g->flags & GPIO_PULL) { /* With pull up/down */ if (g->flags & GPIO_HIGH) |