linux-kernel - Re: [PATCH v13 3/6] clk: Make clk API return per-user struct clk instances

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Date:	Fri, 6 Feb 2015 00:42:10 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	Paul Walmsley <paul@...an.com>,
	Tony Lindgren <tony@...mide.com>, linux-kernel@...r.kernel.org,
	Mike Turquette <mturquette@...aro.org>,
	linux-omap@...r.kernel.org,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v13 3/6] clk: Make clk API return per-user struct clk
 instances

On Thu, Feb 05, 2015 at 02:14:01PM -0800, Stephen Boyd wrote:
> Actually we can bury the __clk_create_clk() inside
> __of_clk_get_from_provider(). We should also move __clk_get() into there
> because right now we have a hole where whoever calls
> of_clk_get_from_provider() never calls __clk_get() on the clk, leading
> to possible badness. v2 coming soon.

There's some other issues here too...

sound/soc/kirkwood/kirkwood-i2s.c:

        priv->clk = devm_clk_get(&pdev->dev, np ? "internal" : NULL);
...
        priv->extclk = devm_clk_get(&pdev->dev, "extclk");
        if (IS_ERR(priv->extclk)) {
...
	} else {
                if (priv->extclk == priv->clk) {
                        devm_clk_put(&pdev->dev, priv->extclk);
                        priv->extclk = ERR_PTR(-EINVAL);
                } else {
                        dev_info(&pdev->dev, "found external clock\n");
                        clk_prepare_enable(priv->extclk);
                        soc_dai = kirkwood_i2s_dai_extclk;
                }

It should be fine provided your "trick" is only done for DT clocks,
but not for legacy - with legacy, a NULL in the clkdev tables will
match both these requests, hence the need to compare the clk_get()
return value to tell whether we get the same clock.

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