[PATCH v2 1/9] mmc: meson-gx: fix setting f_min
hkallweit1 at gmail.com
Sat Feb 4 14:12:32 PST 2017
Am 03.02.2017 um 09:29 schrieb Ulf Hansson:
> On 1 February 2017 at 07:48, Heiner Kallweit <hkallweit1 at gmail.com> 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 at gmail.com>
>> Acked-by: Kevin Hilman <khilman at baylibre.com>
>> - added acked-by
>> 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);
>> - f_min = 4000000; /* default min: 400 MHz */
>> + f_min = 400000; /* default min: 400 kHz */
>> host->mmc->f_min = f_min;
> This hole thing looks really weird to me. Although instead of
> discussing it here, I decided to post a patch to show how I think this
> should be done. Could you please have look!?
Thanks for the patch. Two remarks:
Member mux_parent_rate of struct meson_host is unused after this patch.
So it should be removed as part of the patch.
Requesting 100kHz resulted in f_min = 0 in my tests. Same for 200kHz
and 300 kHz. 400kHz results in f_min = 400kHz with actual rate = 380kHz.
380kHz = 24MHz / 63 is the lowest possible frequency on Meson anyway.
All requested frequencies below this value seem to be rounded down to 0.
Therefore I'd suggest to set the requested rate to 400kHz.
> Kind regards
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