[PATCH] clk: fix clk-gpio.c with optional clock= DT property

[Russell King - ARM Linux]

On Sat, Jan 02, 2016 at 10:01:34AM +0000, Russell King wrote:
> When the clock DT property is not given, of_clk_get_parent_count()
> returns -ENOENT, which then tries to allocate -2 x 4 bytes of memory,
> which of course fails, causing the whole driver to fail to create
> the clock.
> 
> This causes the SolidRun platforms to fail probing the SDHCI1 interface
> which is connected to the WiFi.
> 
> Fix this by detecting errno codes, skipping the allocation, and fixing
> of_clk_gpio_gate_delayed_register_get() to handle a NULL parent_names
> array.
> 
> Fixes: 80eeb1f0f757 ("clk: add gpio controlled clock multiplexer")
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> ---
> This goes all the way back to 80eeb1f0f757 ("clk: add gpio controlled
> clock multiplexer") introduced in June in v4.3-rc2 - which raises the
> question why _development_ work in clk is being merged outside of the
> merge window.
> 
> A rewrite of this patch will be necessary to apply to v4.3 kernels.
> 
> This applies on top of v4.4-rc6.
> 
>  drivers/clk/clk-gpio.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
> index 335322dc403f..05cca9298f44 100644
> --- a/drivers/clk/clk-gpio.c
> +++ b/drivers/clk/clk-gpio.c
> @@ -264,8 +264,8 @@ static struct clk *of_clk_gpio_gate_delayed_register_get(const char *name,
>  		const char * const *parent_names, u8 num_parents,
>  		unsigned gpio, bool active_low)
>  {
> -	return clk_register_gpio_gate(NULL, name, parent_names[0],
> -			gpio, active_low, 0);
> +	return clk_register_gpio_gate(NULL, name, parent_names ?
> +			parent_names[0] : NULL, gpio, active_low, 0);
>  }
>  
>  static struct clk *of_clk_gpio_mux_delayed_register_get(const char *name,
> @@ -292,13 +292,18 @@ static void __init of_gpio_clk_setup(struct device_node *node,
>  		return;
>  
>  	num_parents = of_clk_get_parent_count(node);
> -
> -	parent_names = kcalloc(num_parents, sizeof(char *), GFP_KERNEL);
> -	if (!parent_names)
> -		return;
> -
> -	for (i = 0; i < num_parents; i++)
> -		parent_names[i] = of_clk_get_parent_name(node, i);
> +	if (num_parents > 0) {
> +		parent_names = kcalloc(num_parents, sizeof(char *), GFP_KERNEL);
> +		if (!parent_names) {
> +			kfree(data);
> +			return;
> +		}
> +
> +		for (i = 0; i < num_parents; i++)
> +			parent_names[i] = of_clk_get_parent_name(node, i);
> +	} else {
> +		parent_names = NULL;
> +	}
>  
>  	data->num_parents = num_parents;
>  	data->parent_names = parent_names;
> -- 
> 2.1.0

Yes, indeed, my patch above which fixed clk-gpio.c as can be seen above
does not have the problem that I'm currently seeing...

-- 
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