Re: [PATCH v3 1/2] mfd: arizona: Update reset pin to use GPIOD

On Wed, 07 Mar 2018, Charles Keepax wrote:

On Wed, Mar 07, 2018 at 01:28:12PM +0000, Lee Jones wrote:

quoted

On Tue, 20 Feb 2018, Charles Keepax wrote:

quoted

+	if (IS_ERR(pdata->reset)) {
+		ret = PTR_ERR(pdata->reset);
+		switch (ret) {
+		case -ENOENT:
+		case -ENOSYS:
+			break;
+		case -EPROBE_DEFER:
+			return ret;
+		default:
+			dev_err(arizona->dev, "Reset GPIO malformed: %d\n",
+				ret);
+			break;
+		}

I haven't seen a switch statement used in the error handling path
before.  There is probably good reason for that.

There are a fair few of them "grep -rI "switch (ret)" | wc -l" ==
205. Although to be fair that has rarely been an argument in
somethings favour.

I didn't say "it has never been done", just that I hadn't seen it.

Besides, 205 uses is a very small amount in kernel code:

`git grep "if (ret" | wc -l` == 74710

quoted

What is the 'default' case?  -EINVAL?

I would guess most of the time yes, but I would rather not assume
that. I can redo this as if's if you prefer it that way? The if is
slightly less lines although I do think the switch is much
clearer as to intent.

if (ret == -EPROBE_DEFER) {
	return ret;
} else if (ret != -ENOENT && ret != -ENOSYS {
	dev_err(arizona->dev, ....);
}

I don't know enough about the API to see why -ENOENT and -ENOSYS do
not deserve error messages.

What do the other users of the API do?

-- 
Lee Jones
Linaro Services Technical Lead
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