From 66983857a54479d76ce6dbd8399e1276698bd3c5 Mon Sep 17 00:00:00 2001
From: San Mehat <san@google.com>
Date: Tue, 11 Nov 2008 09:35:36 -0800
Subject: [PATCH 094/134] mmc: sd: Add new CONFIG_MMC_PARANOID_SD_INIT for enabling retries during SD detection

Signed-off-by: San Mehat <san@google.com>
---
 drivers/mmc/core/Kconfig |    8 ++++++++
 drivers/mmc/core/sd.c    |   24 ++++++++++++++++++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

--- a/drivers/mmc/core/Kconfig
+++ b/drivers/mmc/core/Kconfig
@@ -14,3 +14,11 @@ config MMC_UNSAFE_RESUME
 	  This option is usually just for embedded systems which use
 	  a MMC/SD card for rootfs. Most people should say N here.
 
+config MMC_PARANOID_SD_INIT
+	bool "Enable paranoid SD card initialization (EXPERIMENTAL)"
+	help
+	  If you say Y here, the MMC layer will be extra paranoid
+	  about re-trying SD init requests. This can be a useful
+	  work-around for buggy controllers and hardware. Enable
+	  if you are experiencing issues with SD detection.
+
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -336,7 +336,9 @@ static int mmc_sd_init_card(struct mmc_h
 	int err;
 	u32 cid[4];
 	unsigned int max_dtr;
-
+#ifdef CONFIG_MMC_PARANOID_SD_INIT
+	int retries;
+#endif
 	BUG_ON(!host);
 	WARN_ON(!host->claimed);
 
@@ -439,11 +441,29 @@ static int mmc_sd_init_card(struct mmc_h
 		err = mmc_decode_scr(card);
 		if (err < 0)
 			goto free_card;
-
 		/*
 		 * Fetch switch information from card.
 		 */
+#ifdef CONFIG_MMC_PARANOID_SD_INIT
+		for (retries = 1; retries <= 3; retries++) {
+			err = mmc_read_switch(card);
+			if (!err) {
+				if (retries > 1) {
+					printk(KERN_WARNING
+					       "%s: recovered\n", 
+					       mmc_hostname(host));
+				}
+				break;
+			} else {
+				printk(KERN_WARNING
+				       "%s: read switch failed (attempt %d)\n",
+				       mmc_hostname(host), retries);
+			}
+		}
+#else
 		err = mmc_read_switch(card);
+#endif
+
 		if (err)
 			goto free_card;
 	}
