| Message ID | 1351279246-3923-1-git-send-email-jon-hunter@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Sorry, ignore these ... On 10/26/2012 02:20 PM, Jon Hunter wrote: > From: Kevin Hilman <khilman@ti.com> ... forgot to change the author from Kevin to me. Will re-post. Jon > This change was originally titled "gpio/omap: fix off-mode bug: clear debounce > clock enable mask on free/reset". The title has been updated slightly to > reflect (what should be) the final fix. > > When a GPIO is freed or shutdown, we need to ensure that any debounce settings > are cleared and if the GPIO is the only GPIO in the bank that is currently > using debounce, then disable the debounce clock as well to save power. > > Currently, the debounce settings are not cleared on a GPIO free or shutdown and > so during a context restore on subsequent off-mode transition, the previous > debounce values are restored 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 this, introduce a new function called _clear_gpio_debounce() to clear > any debounce settings when the GPIO is freed or shutdown. If this GPIO is the > last debounce-enabled GPIO in the bank, the debounce will also be cut. > > Please note that we cannot use _gpio_dbck_disable() to disable the debounce > clock because this has been specifically created for the gpio suspend path > and is intended to shutdown the debounce clock while debounce is enabled. > > Special thanks to Kevin Hilman for root causing the bug. This fix is a > collaborative effort with inputs from Kevin Hilman, Grazvydas Ignotas and > Santosh Shilimkar. > > Testing: > - This has been unit tested on an OMAP3430 Beagle board, by requesting a gpio, > enabling debounce and then freeing the gpio and checking the register > contents, the saved register context and the debounce clock state. > - Kevin Hilman tested on 37xx/EVM board which configures GPIO debounce for the > ads7846 touchscreen in its board file using the above sequence, and so was > failing off-mode tests in dynamic idle. Verified that off-mode tests are > passing with this patch. > > Reported-by: Paul Walmsley <paul@pwsan.com> > Cc: Igor Grinberg <grinberg@compulab.co.il> > Cc: Grazvydas Ignotas <notasas@gmail.com> > Cc: Jon Hunter <jon-hunter@ti.com> > Signed-off-by: Jon Hunter <jon-hunter@ti.com> > Reviewed-by: Kevin Hilman <khilman@ti.com> > Tested-by: Kevin Hilman <khilman@ti.com> > Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> > --- > drivers/gpio/gpio-omap.c | 35 +++++++++++++++++++++++++++++++++++ > 1 file changed, 35 insertions(+) > > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c > index 94cbc84..d335af1 100644 > --- a/drivers/gpio/gpio-omap.c > +++ b/drivers/gpio/gpio-omap.c > @@ -251,6 +251,40 @@ static void _set_gpio_debounce(struct gpio_bank *bank, unsigned gpio, > } > } > > +/** > + * _clear_gpio_debounce - clear debounce settings for a gpio > + * @bank: the gpio bank we're acting upon > + * @gpio: the gpio number on this @gpio > + * > + * If a gpio is using debounce, then clear the debounce enable bit and if > + * this is the only gpio in this bank using debounce, then clear the debounce > + * time too. The debounce clock will also be disabled when calling this function > + * if this is the only gpio in the bank using debounce. > + */ > +static void _clear_gpio_debounce(struct gpio_bank *bank, unsigned gpio) > +{ > + u32 gpio_bit = GPIO_BIT(bank, gpio); > + > + if (!bank->dbck_flag) > + return; > + > + if (!(bank->dbck_enable_mask & gpio_bit)) > + return; > + > + bank->dbck_enable_mask &= ~gpio_bit; > + bank->context.debounce_en &= ~gpio_bit; > + __raw_writel(bank->context.debounce_en, > + bank->base + bank->regs->debounce_en); > + > + if (!bank->dbck_enable_mask) { > + bank->context.debounce = 0; > + __raw_writel(bank->context.debounce, bank->base + > + bank->regs->debounce); > + clk_disable(bank->dbck); > + bank->dbck_enabled = false; > + } > +} > + > static inline void set_gpio_trigger(struct gpio_bank *bank, int gpio, > unsigned trigger) > { > @@ -539,6 +573,7 @@ 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); > + _clear_gpio_debounce(bank, gpio); > } > > /* Use disable_irq_wake() and enable_irq_wake() functions from drivers */ >
diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c index 94cbc84..d335af1 100644 --- a/drivers/gpio/gpio-omap.c +++ b/drivers/gpio/gpio-omap.c @@ -251,6 +251,40 @@ static void _set_gpio_debounce(struct gpio_bank *bank, unsigned gpio, } } +/** + * _clear_gpio_debounce - clear debounce settings for a gpio + * @bank: the gpio bank we're acting upon + * @gpio: the gpio number on this @gpio + * + * If a gpio is using debounce, then clear the debounce enable bit and if + * this is the only gpio in this bank using debounce, then clear the debounce + * time too. The debounce clock will also be disabled when calling this function + * if this is the only gpio in the bank using debounce. + */ +static void _clear_gpio_debounce(struct gpio_bank *bank, unsigned gpio) +{ + u32 gpio_bit = GPIO_BIT(bank, gpio); + + if (!bank->dbck_flag) + return; + + if (!(bank->dbck_enable_mask & gpio_bit)) + return; + + bank->dbck_enable_mask &= ~gpio_bit; + bank->context.debounce_en &= ~gpio_bit; + __raw_writel(bank->context.debounce_en, + bank->base + bank->regs->debounce_en); + + if (!bank->dbck_enable_mask) { + bank->context.debounce = 0; + __raw_writel(bank->context.debounce, bank->base + + bank->regs->debounce); + clk_disable(bank->dbck); + bank->dbck_enabled = false; + } +} + static inline void set_gpio_trigger(struct gpio_bank *bank, int gpio, unsigned trigger) { @@ -539,6 +573,7 @@ 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); + _clear_gpio_debounce(bank, gpio); } /* Use disable_irq_wake() and enable_irq_wake() functions from drivers */