[PATCH] mmc: sdhci: Test cd-gpio instead of SDHCI presence when probing

[Chris Ball <cjb@laptop.org>]

From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Previously to this patch, an SDHCI platform that uses a GPIO for
card detection instead of the internal SDHCI_CARD_PRESENT bit on
the presence register would fail to bring up a new card because
logic in sdhci_request() fails the request if that bit is 0.

Some drivers worked around this in various ways: esdhc-imx defines
an IO accessor to fake the presence bit being true, s3c turns on
polling (which stops the SDHCI driver from checking the bit) after
a card's inserted.  But none of this should be necessary; the real
fix is to check whether we're using a GPIO and avoid relying on
the presence bit if so, as this patch implements.

Signed-off-by: Chris Ball <cjb@laptop.org>
---
 drivers/mmc/host/sdhci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index d98b199..0e15c79 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -28,6 +28,7 @@
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/card.h>
+#include <linux/mmc/slot-gpio.h>
 
 #include "sdhci.h"
 
@@ -1293,6 +1294,13 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 		present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
 				SDHCI_CARD_PRESENT;
 
+	/* If we're using a cd-gpio, testing the presence bit might fail. */
+	if (!present) {
+		int ret = mmc_gpio_get_cd(host->mmc);
+		if (ret > 0)
+			present = true;
+	}
+
 	if (!present || host->flags & SDHCI_DEVICE_DEAD) {
 		host->mrq->cmd->error = -ENOMEDIUM;
 		tasklet_schedule(&host->finish_tasklet);
-- 
1.7.11.2



- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child