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

[khilman@deeprootsystems.com (Kevin Hilman)]

From: Kevin Hilman <khilman@ti.com>

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 <paul@pwsan.com>
Cc: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Kevin Hilman <khilman@ti.com>
---
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;
 
 		clk_disable(bank->dbck);
 		bank->dbck_enabled = false;
-- 
1.8.0