Re: [PATCH] clk: Make of_clk_get_parent_name() robust with #clock-cells = 1

From: Michael Turquette
Date: Fri Oct 16 2015 - 08:55:42 EST


Cc'ing Geert.

Quoting Stephen Boyd (2015-10-15 16:19:38)
> If a clock provider has #clock-cells = 1 and we call
> of_clk_get_parent_name() on it we may end up returning the name
> of the provider node if the provider doesn't have a
> clock-output-names property. This doesn't make sense, especially
> when you consider that calling of_clk_get_parent_name() on such a
> node with different indices will return the same name each time.
>
> Let's try getting the clock from the framework via of_clk_get()
> instead, and only fallback to the node name if we have a provider
> with #clock-cells = 0. This way, we can't hand out the same name
> for different clocks when we don't actually know their names.
>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>

Geert,

Does this approach fix the issues you had removing clock-output-names
from your clock provider DTS?

Regards,
Mike

> ---
> drivers/clk/clk.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index b005f666e3a1..a0fe9ca1f0af 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3055,6 +3055,7 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
> u32 pv;
> int rc;
> int count;
> + struct clk *clk;
>
> if (index < 0)
> return NULL;
> @@ -3080,8 +3081,25 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
>
> if (of_property_read_string_index(clkspec.np, "clock-output-names",
> index,
> - &clk_name) < 0)
> - clk_name = clkspec.np->name;
> + &clk_name) < 0) {
> + /*
> + * Best effort to get the name if the clock has been
> + * registered with the framework. If the clock isn't
> + * registered, we return the node name as the name of
> + * the clock as long as #clock-cells = 0.
> + */
> + clk = of_clk_get_from_provider(&clkspec);
> + if (IS_ERR(clk)) {
> + if (clkspec.args_count == 0)
> + clk_name = clkspec.np->name;
> + else
> + clk_name = NULL;
> + } else {
> + clk_name = __clk_get_name(clk);
> + clk_put(clk);
> + }
> + }
> +
>
> of_node_put(clkspec.np);
> return clk_name;
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
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