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

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 detect a new card.

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: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index d98b199..0e15c79 100644 (file)
--- 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);