On Friday 29 June 2012 03:25 AM, Kevin Hilman wrote:

Hi Shubhrajyoti,

Shubhrajyoti Datta [off-list ref] writes:

quoted

Hi Kevin,
Thanks for the patch ,
a doubt below

Thanks for the review.

quoted

On Wed, Jun 27, 2012 at 7:15 AM, Kevin Hilman [off-list ref] wrote:

quoted

In omap_i2c_xfer(), ensure pm_runtime_put() is called, even on
failure.

So the failure means that the usecount is incremented. However the
device was not
enabled. 

Correct.

quoted

In that case could we consider

   void pm_runtime_put_noidle(struct device *dev);
    - decrement the device's usage counter

Which will only decrement the counter and does not try to disable it.

No, that is not needed.

quoted

However I am not sure what happens if you try to disable an already
disabled device.

The runtime PM core already knows that the device is not enabled so will
not need to call the disable hooks.  It already needs this functionality
to support the _get_noresume() and _put_noidle() calls.

I tested this on 3730/OveroSTORM where I was seeing this i2c xfer
failure (and thus a failure in MMC suspend, which uses I2C to control
the regulator.)

Hope that helps clarify,

Thanks a lot for the clarification.

If so, Wolfram, can you queue this up in your i2c-embedded/for-next
branch since this problem was introduced there.

Thanks,

Kevin

quoted

quoted

Without this, after a failed xfer, the runtime PM usecount will have
been incremented, but not decremented

Agree.

quoted

causing the usecount to never
reach zero after a failure.  This keeps the device always runtime PM
enabled which keeps the enclosing power domain active, and prevents
full-chip retention/off from happening during idle.

Reviewed-by: Shubhrajyoti D <redacted>

quoted

quoted

Cc: Shubhrajyoti D <redacted>
Signed-off-by: Kevin Hilman <redacted>
---
This patch applies to current i2c-embedded/for-next branch

 drivers/i2c/busses/i2c-omap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 9895fa7..b105733 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c

@@ -582,7 +582,7 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)

       r = pm_runtime_get_sync(dev->dev);
       if (IS_ERR_VALUE(r))
-               return r;
+               goto out;

       r = omap_i2c_wait_for_bb(dev);
       if (r < 0)
--

1.7.9.2

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