From: Anton Vorontsov <avorontsov@ru.mvista.com>
Date: Mon, 16 Mar 2009 21:13:52 +0000 (+0300)
Subject: sdhci: Add support for card-detection polling
X-Git-Tag: v2.6.30-rc1~209^2~9
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=68d1fb7e229c6f95be4fbbe3eb46b24e41184924;p=cascardo%2Flinux.git

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>
---

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 */