[PATCH v2] mmc: mtk-sd: increase the minimum bus frequency
Peng Fan (OSS)
peng.fan at oss.nxp.com
Tue Apr 6 11:40:30 CEST 2021
> Subject: [PATCH v2] mmc: mtk-sd: increase the minimum bus frequency
Could you please rebase? I am not able to apply this patch.
Thanks,
Peng.
>
> With a 48MHz input clock, the lowest bus frequency can be as low as
> 48000000 / (4 * 4095) = 2930Hz. Such an extremely low frequency will cause
> the mmc framework take seconds to finish the initialization.
>
> Limiting the minimum bus frequency to a slightly higher value can solve the
> issue without any side effects.
>
> Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>
> ---
> drivers/mmc/mtk-sd.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/mmc/mtk-sd.c b/drivers/mmc/mtk-sd.c index
> 3b9c122..626a4d3 100644
> --- a/drivers/mmc/mtk-sd.c
> +++ b/drivers/mmc/mtk-sd.c
> @@ -232,6 +232,8 @@
>
> #define SCLK_CYCLES_SHIFT 20
>
> +#define MIN_BUS_CLK 200000
> +
> #define CMD_INTS_MASK \
> (MSDC_INT_CMDRDY | MSDC_INT_RSPCRCERR |
> MSDC_INT_CMDTMO)
>
> @@ -1639,6 +1641,9 @@ static int msdc_drv_probe(struct udevice *dev)
> else
> cfg->f_min = host->src_clk_freq / (4 * 4095);
>
> + if (cfg->f_min < MIN_BUS_CLK)
> + cfg->f_min = MIN_BUS_CLK;
> +
> cfg->f_max = host->src_clk_freq;
>
> cfg->b_max = 1024;
> --
> 1.9.1
More information about the U-Boot
mailing list