mmc: atmel: Properly fix clock configuration
Timing issue occurs on eMMC not only when modifying the frequency but
also for all the switch command(CMD6). According to the MMC spec waiting
8 clocks after a switch command would be the thing to do.
This patch allows fixing CPU hang observed when trying to changing the
bus width on a eMMC on SAMA5D4.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Marek Vasut <marex@denx.de> # on DENX MA5D4EV
Acked-by: Marek Vasut <marex@denx.de>
Tested-by: Andreas Bießmann <andreas.devel@googlemail.com> # on atngw100
Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>
[fixed minor checkpatch warning]
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/drivers/mmc/gen_atmel_mci.c b/drivers/mmc/gen_atmel_mci.c
index da870c6..0474a15 100644
--- a/drivers/mmc/gen_atmel_mci.c
+++ b/drivers/mmc/gen_atmel_mci.c
@@ -36,6 +36,7 @@
struct mmc_config cfg;
struct atmel_mci *mci;
unsigned int initialized:1;
+ unsigned int curr_clk;
};
/* Read Atmel MCI IP version */
@@ -91,7 +92,10 @@
}
}
-
+ if (version >= 0x500)
+ priv->curr_clk = bus_hz / (clkdiv * 2 + clkodd + 2);
+ else
+ priv->curr_clk = (bus_hz / (clkdiv + 1)) / 2;
blklen &= 0xfffc;
mr = MMCI_BF(CLKDIV, clkdiv);
@@ -118,8 +122,6 @@
if (mmc->card_caps & mmc->cfg->host_caps & MMC_MODE_HS)
writel(MMCI_BIT(HSMODE), &mci->cfg);
- udelay(50);
-
priv->initialized = 1;
}
@@ -323,6 +325,13 @@
}
}
+ /*
+ * After the switch command, wait for 8 clocks before the next
+ * command
+ */
+ if (cmd->cmdidx == MMC_CMD_SWITCH)
+ udelay(8*1000000 / priv->curr_clk); /* 8 clk in us */
+
return 0;
}