Jon Hunter <jon-hunter@xxxxxx> writes: > On 10/24/2012 12:10 PM, Kevin Hilman wrote: >> From: Kevin Hilman <khilman@xxxxxx> >> >> When a GPIO bank is freed or shutdown, ensure that the banks >> dbck_enable_mask is cleared also. Otherwise, context restore on >> subsequent off-mode transition will restore previous value from the >> shadow copies (bank->context.debounce*) leading to mismatch state >> between driver state and hardware state. >> >> This was discovered when board code was doing >> >> gpio_request_one() >> gpio_set_debounce() >> gpio_free() >> >> which was leaving the GPIO debounce settings in a confused state. If >> that GPIO bank is subsequently used with off-mode enabled, bogus state >> would be restored, leaving GPIO debounce enabled which then prevented >> the CORE powerdomain from transitioning. >> >> To fix, ensure that bank->dbck_enable_mask is cleared when the bank >> is freed/shutdown so debounce state doesn't persist. >> >> Special thanks to Grazvydas Ignotas for pointing out a bug in an >> earlier version that would've disabled debounce on any runtime PM >> transition. >> >> Reported-by: Paul Walmsley <paul@xxxxxxxxx> >> Cc: Igor Grinberg <grinberg@xxxxxxxxxxxxxx> >> Cc: Grazvydas Ignotas <notasas@xxxxxxxxx> >> Signed-off-by: Kevin Hilman <khilman@xxxxxx> >> --- >> v2: only clear mask in free/shutdown, not in runtime PM paths, >> clarified changelog >> Applies on v3.7-rc2. >> >> drivers/gpio/gpio-omap.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c >> index 94cbc84..113b167 100644 >> --- a/drivers/gpio/gpio-omap.c >> +++ b/drivers/gpio/gpio-omap.c >> @@ -539,6 +539,7 @@ static void _reset_gpio(struct gpio_bank *bank, int gpio) >> _set_gpio_irqenable(bank, gpio, 0); >> _clear_gpio_irqstatus(bank, gpio); >> _set_gpio_triggering(bank, GPIO_INDEX(bank, gpio), IRQ_TYPE_NONE); >> + bank->dbck_enable_mask = 0; >> } > > Does this need to be ... > > + bank->dbck_enable_mask &= ~(GPIO_BIT(bank, gpio)); > + _gpio_dbck_disable(bank); > > There could be more than one gpio using debounce and so we should only > clear the appropriate bit. Also after clearing a bit we could see if we > can disable the debounce clock too. Sigh, you're right. I'm clearly in too much of a rush with this one. Thanks for taking the time to review. v3 coming right up using your suggestsion after some testing just to be sure it fixes that bug. Kevin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
