Re: [PATCH 1/9] mmc: meson-gx: fix setting f_min

Heiner Kallweit
2017-02-01T20:14:13Z

Am 01.02.2017 um 12:49 schrieb Jaehoon Chung:
> On 02/01/2017 05:57 AM, Heiner Kallweit wrote:
>> Currently f_min is set to 4 MHz whilst the comment states 400 MHz.
>> I think the itention is to set f_min to 400 kHz.
>> Change value and comment accordingly.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> drivers/mmc/host/meson-gx-mmc.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index 5eca88bc..da3cce31 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -268,7 +268,7 @@ static int meson_mmc_clk_init(struct meson_host *host)
>> if (f_min != UINT_MAX)
>> f_min = DIV_ROUND_UP(CLK_SRC_XTAL_RATE, CLK_DIV_MAX);
>> else
>> - f_min = 4000000; /* default min: 400 MHz */
>> + f_min = 400000; /* default min: 400 kHz */
>
> I'm not sure but f_min can be 100KHz by default, not 400KHz.
> Because mmc-core should be try to find frequency from 400KHz to "f_min" value.
>
Actually I wonder how we can ever reach this part of the if clause.
If at least one parent clock is defined and we can get its clock rate
then f_min != UINT_MAX.
Can we think of a case where no parent clock is defined?
And would it make sense at all to proceed in this case?

> Best Regards,
> Jaehoon Chung
>
>> host->mmc->f_min = f_min;
>>
>> /* create the mux */
>>
>
>