Re: [PATCH v2 6/9] mmc: meson-gx: remove unneeded meson_mmc_clk_set in meson_mmc_clk_init

Michał Zegan
2017-02-18T04:04:47Z

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Hello Heiner,

W dniu 16.02.2017 o 20:42, Heiner Kallweit pisze:
> This clk_disable_unprepare isn't right here. At first the condition
> should be "if (ret)" as the disable/unprepare is supposed to be
> executed if the previous command fails.
> And if the previous command fails and meson_mmc_clk_init returns
> an error, then probe jumps to label free_host where we have this
> disable/unprepare already.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> v2:
> - extended commit message
> ---
> drivers/mmc/host/meson-gx-mmc.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 68e76fa8..850b0152 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -320,11 +320,7 @@ static int meson_mmc_clk_init(struct meson_host *host)
> /* Get the nearest minimum clock to 400KHz */
> host->mmc->f_min = clk_round_rate(host->cfg_div_clk, 400000);
>
> - ret = meson_mmc_clk_set(host, host->mmc->f_min);
> - if (!ret)
> - clk_disable_unprepare(host->cfg_div_clk);
> -
> - return ret;
> + return meson_mmc_clk_set(host, host->mmc->f_min);
> }
>
> static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>

I see one problem here.
As you said, if the previous command (that is the meson_mmc_clk_set
function call) fails, then the whole meson_mmc_clk_init returns an error
value, and meson_mmc_probe jumps to free_host and disables the clock there.
But what happens if the clk_prepare_enable is the line that fails? in
this case, the function returns an error value too, and in the free_host
meson_mmc_probe tries to disable the clock that is not enabled, and that
probably results in a kernel warning because you tried to disable a
disabled clock.
I was preparing a patch to disable clocks in the probe function only if
they were enabled before, but then the meson_mmc_clk_init function
remains a problem, because we don't know if the clock was enabled
successfully or not when it returns an error.

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