[PATCH v3] i2c: designware: add reset interface

On Wed, 2017-01-04 at 15:55 +0100, Arnd Bergmann wrote:

On Friday, December 23, 2016 9:40:51 PM CET Zhangfei Gao wrote:

quoted

@@ -176,6 +177,14 @@ static int dw_i2c_plat_probe(struct

platform_device *pdev)
????????dev->irq = irq;
????????platform_set_drvdata(pdev, dev);
?
+???????dev->rst = devm_reset_control_get_optional_exclusive(&pdev-

quoted

dev, NULL);

+???????if (IS_ERR(dev->rst)) {
+???????????????if (PTR_ERR(dev->rst) == -EPROBE_DEFER)
+???????????????????????return -EPROBE_DEFER;
+???????} else {
+???????????????reset_control_deassert(dev->rst);
+???????}
+

Sorry for the late reply, I only now stumbled over this. I think it's
generally wrong to ignore any error aside from -EPROBE_DEFER. It's
better to single-out the error conditions you want to ignore (e.g.
no reset specified) and ignore those but return an error for
all other problems.

Which means that reset framework whenever work _optional is used should
return error iff (mind two f:s) there is a problem with existing
control.

quoted

@@ -270,10 +280,18 @@ static int dw_i2c_plat_probe(struct

platform_device *pdev)
????????}
?
????????r = i2c_dw_probe(dev);
-???????if (r && !dev->pm_runtime_disabled)
-???????????????pm_runtime_disable(&pdev->dev);
+???????if (r)
+???????????????goto exit_probe;
?
????????return r;
+
+exit_probe:
+???????if (!dev->pm_runtime_disabled)
+???????????????pm_runtime_disable(&pdev->dev);
+exit_reset:
+???????if (!IS_ERR_OR_NULL(dev->rst))
+???????????????reset_control_assert(dev->rst);
+???????return r;

try to avoid the IS_ERR_OR_NULL() check, it usually indicates either
a bad interface, or that the interface is used wrong.

Please, fix reset framework first than.

For my understanding:
It should return NULL for optional reset control.
It should not fail on NULL argument.

In this case, I think we can't get here with a NULL dev->rst
pointer, so it's better to only check IS_ERR, or to explicitly
set the pointer to NULL in case there is no reset line.

	Arnd

-- 
Andy Shevchenko [off-list ref]
Intel Finland Oy