Subject: [PATCH] gpio/omap: fix off-mode bug: clear debounce clock enable mask on disable

From: [email-masked] (Felipe Balbi)
Date: Wed, 24 Oct 2012 10:39:27 +0300

On Tue, Oct 23, 2012 at 03:00:09PM -0700, Kevin Hilman wrote:
> Felipe Balbi <[email-masked]> writes:
> 
> > Hi,
> >
> > On Tue, Oct 23, 2012 at 11:09:31AM -0700, Kevin Hilman wrote:
> >> From: Kevin Hilman <[email-masked]>
> >> 
> >> When debounce clocks are disabled, 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.
> >> Then, enabling off mode causing bogus state to be restored, leaving
> >> GPIO debounce enabled which then prevented the CORE powerdomain from
> >> transitioning.
> >> 
> >> Reported-by: Paul Walmsley <[email-masked]>
> >> Cc: Igor Grinberg <[email-masked]>
> >> Signed-off-by: Kevin Hilman <[email-masked]>
> >
> > looks like this deserves a Cc: stable at vger.kernel.org tag.
> >
> 
> Agreed.  I think this goes all the way back to v3.5, but would've only
> been seen on boards using a request/gpio_set_debounce/free sequence
> combined with off-mode.
> 
> Linus, feel free to add the Cc: stable when commiting.  Thanks.
> 
> >> ---
> >> Applies on v3.7-rc2, targetted for v3.7.
> >> 
> >>  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..dee2856 100644
> >> --- a/drivers/gpio/gpio-omap.c
> >> +++ b/drivers/gpio/gpio-omap.c
> >> @@ -187,6 +187,7 @@ static inline void _gpio_dbck_disable(struct gpio_bank *bank)
> >>  		 * to detect events and generate interrupts at least on OMAP3.
> >>  		 */
> >>  		__raw_writel(0, bank->base + bank->regs->debounce_en);
> >> +		bank->dbck_enable_mask = 0;
> >
> > shouldn't omap_gpio_restore_context() check for dbck_enabled instead of
> > the mask ? I mean:
> >
> > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> > index 94cbc84..b3a39a7 100644
> > --- a/drivers/gpio/gpio-omap.c
> > +++ b/drivers/gpio/gpio-omap.c
> > @@ -1371,7 +1371,7 @@ static void omap_gpio_restore_context(struct gpio_bank *bank)
> >  				bank->base + bank->regs->dataout);
> >  	__raw_writel(bank->context.oe, bank->base + bank->regs->direction);
> >  
> > -	if (bank->dbck_enable_mask) {
> > +	if (bank->dbck_enabled) {
> >  		__raw_writel(bank->context.debounce, bank->base +
> >  					bank->regs->debounce);
> >  		__raw_writel(bank->context.debounce_en,
> >
> > the outcome would be the same, so it doesn't really matter. Just that,
> > at least to me, it would look better.
> 
> I tried your version, and unfortunately, the outcome is not the same,
> but don't plan to look into why.  $SUBJECT version is targetted and
> tested.  If you want to cleanup the cosmetics here, please do in a
> subsequent patch.  This driver could certainly benefit from more
> readability cleanups.
> 
> > No strong feelings though.
> 
> Good.   I'll take that as an Ack.  :)

please do:

Acked-by: Felipe Balbi <[email-masked]>

-- 
balbi
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