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 --- drivers/mmc/gen_atmel_mci.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/mmc/gen_atmel_mci.c b/drivers/mmc/gen_atmel_mci.c index da870c6..3f7cfba 100644 --- a/drivers/mmc/gen_atmel_mci.c +++ b/drivers/mmc/gen_atmel_mci.c @@ -36,6 +36,7 @@ struct atmel_mci_priv { 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 @@ static void mci_set_mode(struct mmc *mmc, u32 hz, u32 blklen)
} } - + 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 @@ static void mci_set_mode(struct mmc *mmc, u32 hz, u32 blklen) if (mmc->card_caps & mmc->cfg->host_caps & MMC_MODE_HS) writel(MMCI_BIT(HSMODE), &mci->cfg);
- udelay(50); - priv->initialized = 1; }
@@ -284,8 +286,10 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data) { u32 cnt = word_count * 4; printf("Read Data:\n"); + /* print_buffer(0, data->dest + cnt * block_count, 1, cnt, 0); + */ } #endif #ifdef DEBUG @@ -323,6 +327,12 @@ mci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd, struct mmc_data *data) } }
+ /* 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; }