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mmc: mtk-sd: increase the minimum bus frequency

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.

Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
Weijie Gao 3 年 前
コミット
3a3672cc37
1 ファイル変更5 行追加0 行削除
  1. 5 0
      drivers/mmc/mtk-sd.c

+ 5 - 0
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;
+
 	if (cfg->f_max < cfg->f_min || cfg->f_max > host->src_clk_freq)
 		cfg->f_max = host->src_clk_freq;