linux-kernel - Re: [RFC PATCH 3/5] of: add clock providers

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Date:	Wed, 26 Jan 2011 14:47:09 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	devicetree-discuss@...ts.ozlabs.org, jeremy.kerr@...onical.com,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	nicolas.pitre@...aro.org
Subject: Re: [RFC PATCH 3/5] of: add clock providers

On Tue, Jan 25, 2011 at 09:44:17PM -0700, Grant Likely wrote:
> +struct clk *of_clk_get(struct device *dev, const char *id)
> +{
...
> +	snprintf(prop_name, 32, "%s-clock", id ? id : "bus");
> +	prop = of_get_property(dev->of_node, prop_name, &sz);
> +	if (!prop || sz < 4)
> +		return NULL;
...
> +	 * size of the property. */
> +	if (strlen(prop) + 1 > sz)
> +		return NULL;
> +
> +	/* Find the clock provider node; check if it is registered as a
> +	 * provider, and ask it for the relevant clk structure */
> +	provnode = of_find_node_by_phandle(provhandle);
> +	if (!provnode) {
> +		pr_warn("%s: %s property in node %s references invalid phandle",
> +			__func__, prop_name, dev->of_node->full_name);
> +		return NULL;
...

> +	return clk;
> +}

On Tue, Jan 25, 2011 at 09:44:22PM -0700, Grant Likely wrote:
> @@ -79,6 +81,11 @@ EXPORT_SYMBOL(clk_get_sys);
>  struct clk *clk_get(struct device *dev, const char *con_id)
>  {
>  	const char *dev_id = dev ? dev_name(dev) : NULL;
> +	struct clk *clk;
> +
> +	clk = of_clk_get(dev, con_id);
> +	if (clk && __clk_get(clk))
> +		return clk;
>  
>  	return clk_get_sys(dev_id, con_id);
>  }
> 

The return value for clk_get() by almost all users is checked for
specifically with IS_ERR() rather than an IS_ERR_OR_NULL(), so you're
going to want to change your of_clk_get() error paths to return
ERR_PTR()'s directly, or wrap it up like clk_get_sys() does.

Given that there are multiple reasons why of_clk_get() can fail however,
it's probably worth handing down the actual error rather than simply
chomping it in to an -ENOENT.
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