[PATCH] mmc: allow skipping SD card initialization

[Philipp Zabel]

This patch allows to skip SD card initialization for eMMCs by setting
the "no-sd" property in the host controller device tree node. Avoiding
two SD command timeouts speeds up detection time by well over 200 ms.

Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
---
 drivers/mci/mci-core.c | 12 ++++++++----
 include/mci.h          |  1 +
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index 07911d43d..208b7666d 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -1682,10 +1682,13 @@ static int mci_card_probe(struct mci *mci)
 	}
 
 	/* Check if this card can handle the "SD Card Physical Layer Specification 2.0" */
-	rc = sd_send_if_cond(mci);
-	rc = sd_send_op_cond(mci);
-	if (rc && rc == -ETIMEDOUT) {
-		/* If the command timed out, we check for an MMC card */
+	if (!host->no_sd) {
+		rc = sd_send_if_cond(mci);
+		rc = sd_send_op_cond(mci);
+	}
+	if (host->no_sd || rc == -ETIMEDOUT) {
+		/* If SD card initialization was skipped or if it timed out,
+		 * we check for an MMC card */
 		dev_dbg(&mci->dev, "Card seems to be a MultiMediaCard\n");
 		rc = mmc_send_op_cond(mci);
 	}
@@ -1904,6 +1907,7 @@ void mci_of_parse_node(struct mci_host *host,
 	}
 
 	host->non_removable = of_property_read_bool(np, "non-removable");
+	host->no_sd = of_property_read_bool(np, "no-sd");
 }
 
 void mci_of_parse(struct mci_host *host)
diff --git a/include/mci.h b/include/mci.h
index d3115e8cc..1f6533391 100644
--- a/include/mci.h
+++ b/include/mci.h
@@ -403,6 +403,7 @@ struct mci_host {
 	unsigned dsr_val;	/**< optional dsr value */
 	int use_dsr;		/**< optional dsr usage flag */
 	bool non_removable;	/**< device is non removable */
+	bool no_sd;		/**< do not send SD commands during initialization */
 	struct regulator *supply;
 
 	/** init the host interface */
-- 
2.11.0