From 3332acd9089ba21a16570a149c207d37bb910dec Mon Sep 17 00:00:00 2001
From: Sonic Zhang <sonic.zhang@analog.com>
Date: Mon, 12 Jul 2010 15:50:56 +0800
Subject: [PATCH] --- yaml --- r: 219031 b: refs/heads/master c:
 061c6c847eeb11743e489a16e907b41c6f9042b6 h: refs/heads/master i:   219029:
 5580ee39bf6a35ba314b7e610e05c5f8192bfe25   219027:
 cfdc7a4a05d9e7de383383e8c2d7ba39bef223ea   219023:
 c3589dbce897641a24c5895dead20412acfa4024 v: v3

---
 [refs]                           |  2 +-
 trunk/drivers/mmc/host/mmc_spi.c | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 370a236fb1ac..8829f075e5d8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 95f25efe0ce22e28d61722d655d2ef582f5f7520
+refs/heads/master: 061c6c847eeb11743e489a16e907b41c6f9042b6
diff --git a/trunk/drivers/mmc/host/mmc_spi.c b/trunk/drivers/mmc/host/mmc_spi.c
index 5b0b50636ec4..fd877f633dd2 100644
--- a/trunk/drivers/mmc/host/mmc_spi.c
+++ b/trunk/drivers/mmc/host/mmc_spi.c
@@ -1055,6 +1055,8 @@ static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
 {
 	struct mmc_spi_host	*host = mmc_priv(mmc);
 	int			status = -EINVAL;
+	int			crc_retry = 5;
+	struct mmc_command	stop;
 
 #ifdef DEBUG
 	/* MMC core and layered drivers *MUST* issue SPI-aware commands */
@@ -1087,10 +1089,29 @@ static void mmc_spi_request(struct mmc_host *mmc, struct mmc_request *mrq)
 	/* request exclusive bus access */
 	spi_bus_lock(host->spi->master);
 
+crc_recover:
 	/* issue command; then optionally data and stop */
 	status = mmc_spi_command_send(host, mrq, mrq->cmd, mrq->data != NULL);
 	if (status == 0 && mrq->data) {
 		mmc_spi_data_do(host, mrq->cmd, mrq->data, mrq->data->blksz);
+
+		/*
+		 * The SPI bus is not always reliable for large data transfers.
+		 * If an occasional crc error is reported by the SD device with
+		 * data read/write over SPI, it may be recovered by repeating
+		 * the last SD command again. The retry count is set to 5 to
+		 * ensure the driver passes stress tests.
+		 */
+		if (mrq->data->error == -EILSEQ && crc_retry) {
+			stop.opcode = MMC_STOP_TRANSMISSION;
+			stop.arg = 0;
+			stop.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
+			status = mmc_spi_command_send(host, mrq, &stop, 0);
+			crc_retry--;
+			mrq->data->error = 0;
+			goto crc_recover;
+		}
+
 		if (mrq->stop)
 			status = mmc_spi_command_send(host, mrq, mrq->stop, 0);
 		else