Re: [PATCH v2] clk: let clk_disable() return immediately if clk is NULL or error

Stephen Boyd
2016-04-14T00:33:41Z

On 04/08, Masahiro Yamada wrote:
>
>
> This makes our driver programming life easier.
>
>
> For example, let's see drivers/tty/serial/8250/8250_of.c
>
>
> The "clock-frequency" DT property takes precedence over "clocks" property.
> So, it is valid to probe the driver with a NULL pointer for info->clk.
>
>
> if (of_property_read_u32(np, "clock-frequency", &clk)) {
>
> /* Get clk rate through clk driver if present */
> info->clk = devm_clk_get(&ofdev->dev, NULL);
> if (IS_ERR(info->clk)) {
> dev_warn(&ofdev->dev,
> "clk or clock-frequency not defined\n");
> return PTR_ERR(info->clk);
> }
>
> ret = clk_prepare_enable(info->clk);
> if (ret < 0)
> return ret;
>
> clk = clk_get_rate(info->clk);
> }
>
>
> As a result, we need to make sure the clk pointer is valid
> before calling clk_disable_unprepare().
>
>
> If we could support pointer checking in callees, we would be able to
> clean-up lots of clock consumers.
>
>

I'm not sure if you meant to use that example for the error
pointer case? It bails out if clk_get() returns an error pointer.

I'm all for a no-op in clk_disable()/unprepare() when the pointer
is NULL. But when it's an error pointer the driver should be
handling it and bail out before it would ever call enable/prepare
on it or disable/unprepare.

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