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

[Heiner Kallweit]

Am 18.02.2017 um 04:44 schrieb Michał Zegan:
> 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 at 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.
> 
Thanks for pointing out, you're right. The solution however should be
quite easy. I meson_mmc_clk_init we just change the condition of
the disable/unprepare to "if (ret)" and in probe we remove this
disable/unprepare from the error path.