sdhci: Add support for card-detection polling

This patch adds SDHCI_QUIRK_BROKEN_CARD_DETECTION quirk. When specified,
sdhci driver will set MMC_CAP_NEEDS_POLL MMC host capability, and won't
enable card insert/remove interrupts.

This is needed for hosts with unreliable card detection, such as FSL
eSDHC. The original eSDHC driver was tring to "debounce" card-detection
IRQs by reading present state and disabling particular interrupts. But
with this debouncing scheme I noticed that sometimes we miss card
insertion/removal events.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

2 files changed, 17 insertions, 2 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6fbbc005dd7f..fc7cb489bdb7 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -112,6 +112,9 @@ static void sdhci_set_card_detection(struct sdhci_host *host, bool enable)
 {
         u32 irqs = SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT;
 
+        if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
+                return;
+
         if (enable)
                 sdhci_unmask_irqs(host, irqs);
         else
@@ -1041,6 +1044,7 @@ out:
 static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 {
         struct sdhci_host *host;
+        bool present;
         unsigned long flags;
 
         host = mmc_priv(mmc);
@@ -1055,8 +1059,14 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 
         host->mrq = mrq;
 
-        if (!(sdhci_readl(host, SDHCI_PRESENT_STATE) & SDHCI_CARD_PRESENT)
-                || (host->flags & SDHCI_DEVICE_DEAD)) {
+        /* If polling, assume that the card is always present. */
+        if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
+                present = true;
+        else
+                present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
+                                SDHCI_CARD_PRESENT;
+
+        if (!present || host->flags & SDHCI_DEVICE_DEAD) {
                 host->mrq->cmd->error = -ENOMEDIUM;
                 tasklet_schedule(&host->finish_tasklet);
         } else
@@ -1690,6 +1700,9 @@ int sdhci_add_host(struct sdhci_host *host)
         if (caps & SDHCI_CAN_DO_HISPD)
                 mmc->caps |= MMC_CAP_SD_HIGHSPEED;
 
+        if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
+                mmc->caps |= MMC_CAP_NEEDS_POLL;
+
         mmc->ocr_avail = 0;
         if (caps & SDHCI_CAN_VDD_330)
                 mmc->ocr_avail |= MMC_VDD_32_33|MMC_VDD_33_34;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index a9e25c6c0c0e..968d713950f1 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -214,6 +214,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_BROKEN_SMALL_PIO                    (1<<13)
 /* Controller does not provide transfer-complete interrupt when not busy */
 #define SDHCI_QUIRK_NO_BUSY_IRQ                         (1<<14)
+/* Controller has unreliable card detection */
+#define SDHCI_QUIRK_BROKEN_CARD_DETECTION               (1<<15)
 
         int                     irq;            /* Device IRQ */
         void __iomem *          ioaddr;         /* Mapped address */