[PATCH 3/3] MMC compatibility fix - OCR mask

[Pierre Ossman]

This patch avoids using a emtpy OCR mask for the initial power up. Since 
some cards do not like a one bit-mask a routine has been added which 
grows the mask to three bits (one extra bit on each side) if necessary.

Index: linux-wbsd/drivers/mmc/mmc.c
===================================================================
--- linux-wbsd/drivers/mmc/mmc.c	(revision 63)
+++ linux-wbsd/drivers/mmc/mmc.c	(revision 64)
@@ -300,6 +300,31 @@
 	return ocr;
 }
 
+/*
+ * Calculate a OCR mask to use for initial scanning.
+ * All zeroes and all ones cannot be used with some cards.
+ * Just on bit cannot be used either so extend the OCR
+ * if needed.
+ */
+
+static u32 mmc_select_scan_ocr(struct mmc_host *host)
+{
+	u32 ocr;
+
+	ocr = host->ocr_avail;
+
+	/* Check if we have more than one bit */
+	if (ocr & (ocr << 1))
+		return ocr;
+	if (ocr & (ocr >> 1))
+		return ocr;
+
+	/* Extend the mask to surrounding bits */
+	ocr |= (ocr << 1) | (ocr >> 1);
+
+	return ocr;
+}
+
 static void mmc_decode_cid(struct mmc_cid *cid, u32 *resp)
 {
 	memset(cid, 0, sizeof(struct mmc_cid));
@@ -589,7 +614,9 @@
 
 		mmc_power_up(host);
 
-		err = mmc_send_op_cond(host, 0, &ocr);
+		ocr = mmc_select_scan_ocr(host);
+
+		err = mmc_send_op_cond(host, ocr, &ocr);
 		if (err != MMC_ERR_NONE)
 			return;