[U-Boot] [PATCH] mmc: fix OCR Polling

[Peng Fan]

If in mmc_send_op_cond, OCR_BUSY is set in CMD1's response, then
state is transfered to Ready state, and there is no need to send
CMD1 again. Otherwise following CMD1 will recieve no response, or
timeour error from driver such as fsl_esdhc.c.

If not into Ready state in previous CMD1, then continue CMD1 command.

In mmc_complete_op_cond, we use the value mmc->op_cond_response
from mmc_send_op_cond, since there should be no CMD1 command between
mmc_send_op_cond and mmc_complete_op_cond

Before fixing this, uboot log shows:
"
CMD_SEND:0
                ARG                      0x00000000
                MMC_RSP_NONE
CMD_SEND:8
                ARG                      0x000001AA
                MMC_RSP_R1,5,6,7         0x18EC1504
CMD_SEND:55
                ARG                      0x00000000
                MMC_RSP_R1,5,6,7         0x18EC1504
CMD_SEND:0
                ARG                      0x00000000
                MMC_RSP_NONE
CMD_SEND:1
                ARG                      0x00000000
                MMC_RSP_R3,4             0x00FF8080
CMD_SEND:1
                ARG                      0x40300000
                MMC_RSP_R3,4             0xC0FF8080 --> Already OCR_BUSY set
CMD_SEND:1
                ARG                      0x40300000
                MMC_RSP_R3,4             0x0096850A --> Failed CMD1
MMC init failed
"

Using this patch, this issue is fixed, emmc can be detected correctly.


Signed-off-by: Peng Fan <Peng.Fan at freescale.com>
---
 drivers/mmc/mmc.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index a13769e..43a9a8a 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -406,14 +406,23 @@ static int mmc_complete_op_cond(struct mmc *mmc)
 
 	mmc->op_cond_pending = 0;
 	start = get_timer(0);
-	do {
+	/*
+	 * If in mmc_send_op_cond, OCR_BUSY is set in CMD1's response, then
+	 * state is transfered to Ready state, and there is no need to
+	 * send CMD1 again. Otherwise following CMD1 will recieve no response,
+	 * or timeour error from driver such as fsl_esdhc.c.
+	 *
+	 * If not into Ready state in previous CMD1, then continue CMD1
+	 * command.
+	 */
+	while (!(mmc->op_cond_response & OCR_BUSY)) {
 		err = mmc_send_op_cond_iter(mmc, &cmd, 1);
 		if (err)
 			return err;
 		if (get_timer(start) > timeout)
 			return UNUSABLE_ERR;
 		udelay(100);
-	} while (!(mmc->op_cond_response & OCR_BUSY));
+	}
 
 	if (mmc_host_is_spi(mmc)) { /* read OCR for spi */
 		cmd.cmdidx = MMC_CMD_SPI_READ_OCR;
-- 
1.8.4