On Thursday 08 May 2014 02:56 PM, Javier Martinez Canillas wrote:

Hello Rajendra,

On Thu, May 8, 2014 at 9:06 AM, Rajendra Nayak [off-list ref] wrote:

quoted

On Wednesday 23 April 2014 11:41 AM, Rajendra Nayak wrote:

quoted

Replace the clk_enable()s with a clk_prepare_enable() and
the clk_disables()s with a clk_disable_unprepare()

This never showed issues due to the OMAP platform code (hwmod)
leaving these clocks in clk_prepare()ed state by default.

Reported-by: Kishon Vijay Abraham I <redacted>
Signed-off-by: Rajendra Nayak <redacted>
Cc: linux-gpio at vger.kernel.org
Cc: Santosh Shilimkar <redacted>
Cc: Kevin Hilman <redacted>

Linus,

Do you mind picking this fix up via the GPIO tree? Alternatively you could
Ack this if you are fine and we can take both Patch 1/2 and Patch 2/2 from this
series via the OMAP tree.

Patch 2/2 has a dependency on Patch 1/2 and they need to go in in that order else
gpio would break. More discussions are here [1].
Let us know what you think. Thanks.

I wonder if that is really the case. Your Patch 2/2 removes the call
to clk_prepare on _init_opt_clks() but it also replaces
clk_{enable,disable} with clk_prepare_enable()/clk_disable_unprepare()
on _enable_optional_clocks() and _disable_optional_clocks()
respectively.

Right, the difference being, by the time hwmod is done enabling/disabling
the opt clocks, without patch 2/2, the prepare count is 1, with patch 2/2
prepare count is 0.

And GPIO banks are reset by hwmod on init which as far as I know
happen very early before the GPIO OMAP driver is even probed so by the
time clk_enable() is called on the GPIO driver the clock will already
be prepared by _enable_optional_clocks(). I tested linux-gpio/devel

and unprepared by _disable_optional_clocks()?

branch + only your Patch 2/2 and the GPIOs were working correctly on a
OMAP3 board.

Did gpio_debounce() ever get called for any of the gpios?

So I think that there isn't a strict dependency between these two
patches or am I missing something?

In fact now that I think about it I wonder what's the functional
change of your Patch 2/2 since hwmod is still calling clk_prepare()
before the driver. If the clocks should actually be controlled by the

I don't understand why you say 'before the driver'. Hwmod needs to control
optional clocks for some devices in order to do a ocp reset. So it does
touch these optional clocks, but if you look at the code it subsequently
also disables (and unprepares with patch 2/2) these clocks before returning
the control to the driver.

drivers like you said then I think that we should remove
_{enable,disable}_optional_clocks() completely and let the drivers do
the clock prepare and enable like is made on your Patch 1/2 for the
GPIO driver.

What do you think about it?

Best regards,
Javier

quoted

regards,
Rajendra

[1] http://www.mail-archive.com/linux-gpio at vger.kernel.org/msg02801.html

quoted

---
 drivers/gpio/gpio-omap.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 19b886c..78bc5a4 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c

@@ -180,7 +180,7 @@ static inline void _gpio_rmw(void __iomem *base, u32 reg, u32 mask, bool set)
 static inline void _gpio_dbck_enable(struct gpio_bank *bank)
 {
      if (bank->dbck_enable_mask && !bank->dbck_enabled) {
-             clk_enable(bank->dbck);
+             clk_prepare_enable(bank->dbck);
              bank->dbck_enabled = true;

              writel_relaxed(bank->dbck_enable_mask,

@@ -198,7 +198,7 @@ static inline void _gpio_dbck_disable(struct gpio_bank *bank)
               */
              writel_relaxed(0, bank->base + bank->regs->debounce_en);

-             clk_disable(bank->dbck);
+             clk_disable_unprepare(bank->dbck);
              bank->dbck_enabled = false;
      }
 }

@@ -231,7 +231,7 @@ static void _set_gpio_debounce(struct gpio_bank *bank, unsigned gpio,

      l = GPIO_BIT(bank, gpio);

-     clk_enable(bank->dbck);
+     clk_prepare_enable(bank->dbck);
      reg = bank->base + bank->regs->debounce;
      writel_relaxed(debounce, reg);

@@ -245,7 +245,7 @@ static void _set_gpio_debounce(struct gpio_bank *bank, unsigned gpio,
      bank->dbck_enable_mask = val;

      writel_relaxed(val, reg);
-     clk_disable(bank->dbck);
+     clk_disable_unprepare(bank->dbck);
      /*
       * Enable debounce clock per module.
       * This call is mandatory because in omap_gpio_request() when

@@ -290,7 +290,7 @@ static void _clear_gpio_debounce(struct gpio_bank *bank, unsigned gpio)
              bank->context.debounce = 0;
              writel_relaxed(bank->context.debounce, bank->base +
                           bank->regs->debounce);
-             clk_disable(bank->dbck);
+             clk_disable_unprepare(bank->dbck);
              bank->dbck_enabled = false;
      }
 }

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