linux-kernel - [PATCH] mmc: Add delay between CMD6 and CMD13 for Sandisk eMMC cards

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Date:	Tue,  9 Sep 2014 14:26:54 +0200
From:	Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>
To:	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Cc:	tgih.jun@...sung.com, ulf.hansson@...aro.org, chris@...ntf.net,
	Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>
Subject: [PATCH] mmc: Add delay between CMD6 and CMD13 for Sandisk eMMC cards

Tested on a i.MX6 board, with Sandisk SDIN5D1-2G.
Without this patch, I/O errors occur.
This eMMC seems to have a different Manufacturer ID as it reads 0x45
and not 0x2 as specified in datasheet.

Signed-off-by: Jean-Michel Hautbois <jean-michel.hautbois@...alys.com>
---
 drivers/mmc/core/mmc_ops.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index f51b5ba..91babaa 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -458,6 +458,15 @@ int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 	if (!use_busy_signal)
 		return 0;
 
+	/* WORKAROUND: for Sandisk eMMC cards, it might need certain delay
+	 * before sending CMD13 after CMD6
+	 * On SDIN5D1-2G MANFID is 0x45 and not 0x2 as specified in datasheet
+	 */
+	if (card->cid.manfid == CID_MANFID_SANDISK ||
+		card->cid.manfid == 0x45) {
+		msleep(1);
+	}
+
 	/*
 	 * CRC errors shall only be ignored in cases were CMD13 is used to poll
 	 * to detect busy completion.
-- 
2.0.4

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