1 From ed880b7572e1135e3bd8382d4670a375f7d9c91b Mon Sep 17 00:00:00 2001
2 From: Weijie Gao <weijie.gao@mediatek.com>
3 Date: Tue, 2 Mar 2021 15:56:17 +0800
4 Subject: [PATCH 10/21] mmc: mtk-sd: increase the minimum bus frequency
6 With a 48MHz input clock, the lowest bus frequency can be as low as
7 48000000 / (4 * 4095) = 2930Hz. Such an extremely low frequency will cause
8 the mmc framework take seconds to finish the initialization.
10 Limiting the minimum bus frequency to a slightly higher value can solve the
11 issue without any side effects.
13 Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
15 drivers/mmc/mtk-sd.c | 5 +++++
16 1 file changed, 5 insertions(+)
18 --- a/drivers/mmc/mtk-sd.c
19 +++ b/drivers/mmc/mtk-sd.c
22 #define SCLK_CYCLES_SHIFT 20
24 +#define MIN_BUS_CLK 260000
26 #define CMD_INTS_MASK \
27 (MSDC_INT_CMDRDY | MSDC_INT_RSPCRCERR | MSDC_INT_CMDTMO)
29 @@ -1639,6 +1641,9 @@ static int msdc_drv_probe(struct udevice
31 cfg->f_min = host->src_clk_freq / (4 * 4095);
33 + if (cfg->f_min < MIN_BUS_CLK)
34 + cfg->f_min = MIN_BUS_CLK;
36 cfg->f_max = host->src_clk_freq;