From: jon-hunter@ti•com (Jon Hunter)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] gpio/omap: fix off-mode bug: clear debounce clock enable mask on free/reset
Date: Wed, 24 Oct 2012 17:54:15 -0500 [thread overview]
Message-ID: <50887197.8010104@ti.com> (raw)
In-Reply-To: <1351098641-23917-1-git-send-email-khilman@deeprootsystems.com>
On 10/24/2012 12:10 PM, Kevin Hilman wrote:
> From: Kevin Hilman <khilman@ti•com>
>
> 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@pwsan•com>
> Cc: Igor Grinberg <grinberg@compulab•co.il>
> Cc: Grazvydas Ignotas <notasas@gmail•com>
> Signed-off-by: Kevin Hilman <khilman@ti•com>
> ---
> 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.
Cheers
Jon
next prev parent reply other threads:[~2012-10-24 22:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 17:10 [PATCH v2] gpio/omap: fix off-mode bug: clear debounce clock enable mask on free/reset Kevin Hilman
2012-10-24 22:54 ` Jon Hunter [this message]
2012-10-25 7:00 ` Santosh Shilimkar
2012-10-25 13:11 ` Jon Hunter
2012-10-25 13:19 ` Santosh Shilimkar
2012-10-25 16:30 ` Kevin Hilman
2012-10-25 16:49 ` Jon Hunter
2012-10-25 16:26 ` Kevin Hilman
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