[PATCH v3 1/2] i2c: davinci: Add PM Runtime Support

On Tuesday 12 September 2017 01:41 AM, Grygorii Strashko wrote:

On 09/11/2017 03:07 PM, Franklin S Cooper Jr wrote:

quoted

On 09/11/2017 06:29 AM, Sekhar Nori wrote:

quoted

On Friday 08 September 2017 11:24 PM, Franklin S Cooper Jr wrote:

quoted

66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
like other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime

unlike ?

quoted

is required to insure the power domain used by the specific I2C instance is
properly turned on along with its functional clock.

Signed-off-by: Franklin S Cooper Jr <redacted>
---
Version 3 changes:
Remove several statements that set clk to NULL
Fix error path

  drivers/i2c/busses/i2c-davinci.c | 64 +++++++++++++++++++++++++++++++++-------
  1 file changed, 53 insertions(+), 11 deletions(-)

quoted

@@ -802,12 +821,22 @@ static int davinci_i2c_probe(struct platform_device *pdev)
  	dev->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(dev->clk))
  		return PTR_ERR(dev->clk);
-	clk_prepare_enable(dev->clk);
  
  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	dev->base = devm_ioremap_resource(&pdev->dev, mem);
  	if (IS_ERR(dev->base)) {
-		r = PTR_ERR(dev->base);
+		return PTR_ERR(dev->base);
+	}
+
+	pm_runtime_set_autosuspend_delay(dev->dev,
+					 DAVINCI_I2C_PM_TIMEOUT);
+	pm_runtime_use_autosuspend(dev->dev);
+
+	pm_runtime_enable(dev->dev);
+
+	r = pm_runtime_get_sync(dev->dev);
+	if (r < 0) {
+		dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
  		goto err_unuse_clocks;

You end up doing a pm_runtime_put_sync() on failure here, instead of
pm_runtime_put_noidle() like rest of the patch.

May be handle this failure here instead of relying on the goto path.

Ok

I think, it's not necessary - pm_runtime_put_sync() can be used in this case
 (and used the same way in many other drivers).
In case, of failure in this place - pm_runtime_put_sync() will just decrement usage counter.

Can you please explain why this is the case? At least on DA850, I see
the runtime_idle callback invoked from rpm_idle() if
pm_runtime_put_sync() is used in the failure path.

Thanks
Sekhar