FAILED: patch "[PATCH] gpio: zynq: initialize clock even without CONFIG_PM" failed to apply to 4.6-stable tree

The patch below does not apply to the 4.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Helmut Grohne <[email protected]>
Date: Fri, 3 Jun 2016 14:15:32 +0200
Subject: [PATCH] gpio: zynq: initialize clock even without CONFIG_PM

When the PM initialization was moved in the commit referenced below, the code enabling the clock was removed from the probe function. On CONFIG_PM=y kernels, this is not a problem as the pm resume hook enables the clock, but when power management is disabled, all those pm_* functions are noops and the clock is never enabled resulting in a dysfunctional gpio controller.

Put the clock initialization back to support CONFIG_PM=n.

index 75c6355b018d..e72794e463aa 100644
@@ -709,7 +709,13 @@ static int zynq_gpio_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "input clock not found.\n");
 		return PTR_ERR(gpio->clk);
 	}
+	ret = clk_prepare_enable(gpio->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable clock.\n");
+		return ret;
+	}
 
+	pm_runtime_set_active(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
 	ret = pm_runtime_get_sync(&pdev->dev);
 	if (ret < 0)

@@ -747,6 +753,7 @@ err_pm_put:
 	pm_runtime_put(&pdev->dev);
 err_pm_dis:
 	pm_runtime_disable(&pdev->dev);
+	clk_disable_unprepare(gpio->clk);
 
 	return ret;
 }

Hi greg,

Thanks for considering the patch for stable. It seems though that my notes concerning stable have been lost in transmission.

The first observation is that the regression was introduced in 4.4, so no earlier stable trees are affected.

Then I had to rebase my patch, because it touches the same lines as 615d23f80efc ("gpio: zynq: Fix the error path"). My initial patch posting[1] did not consider that patch, so there you go with a rebased patch that applies to earlier kernel versions. I still use that patch successfully for bisecting.

I do note however, that the mentioned "Fix the error path" commit also looks like it should be included into a stable tree, because it fixes an unbalanced pm_runtime_enable. Thus I recommend applying it to stable as well. Then the patch that went into 4.7-rc3 just applies.

Helmut

[1] https://lkml.kernel.org/r/20160601110259.GA30501@laureti-dev

Thanks, I think I have it worked out now.

greg k-h