linux-kernel - Re: [PATCH v2] clk: let of_clk_get_parent_name() fail for invalid clock-indices

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Message-ID: <20151201005802.GE17532@codeaurora.org>
Date:	Mon, 30 Nov 2015 16:58:02 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:	linux-gpio@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] clk: let of_clk_get_parent_name() fail for invalid
 clock-indices

On 11/30, Masahiro Yamada wrote:
> Currently, of_clk_get_parent_name() returns a wrong parent clock name
> when "clock-indices" property exists and the target index is not
> found in the property.  In this case, NULL should be returned.
> 
> For example,
> 
>         oscillator {
>                 compatible = "myclocktype";
>                 #clock-cells = <1>;
>                 clock-indices = <1>, <3>;
>                 clock-output-names = "clka", "clkb";
>         };
> 
>         consumer {
>                 compatible = "myclockconsumer";
>                 clocks = <&oscillator 0>, <&oscillator 1>;
>         };
> 
> Currently, of_clk_get_parent_name(consumer_np, 0) returns "clka"
> (and of_clk_get_parent_name(consumer_np, 1) also returns "clka",
> this is correct).   Because the "clock-indices" in the clock parent
> does not contain <0>, of_clk_get_parent_name(consumer_np, 0) should
> return NULL.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Here's the proposed alternative, if you agree I will merge it
with the above commit text and attribution to you.

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index a66efc9d8bfc..f54583a9835a 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3079,6 +3079,9 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
 		}
 		count++;
 	}
+	/* We went off the end of 'clock-indices' without finding it */
+	if (!vp && count)
+		return NULL;
 
 	if (of_property_read_string_index(clkspec.np, "clock-output-names",
 					  index,

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