[PATCH 04/11] sdhci: Add support for card-detection polling

[Anton Vorontsov]

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 at ru.mvista.com>
---
 drivers/mmc/host/sdhci.c |    6 ++++++
 drivers/mmc/host/sdhci.h |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index b7a79a0..45c5f1f 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -162,6 +162,9 @@ static void sdhci_init(struct sdhci_host *host)
 		SDHCI_INT_DMA_END | SDHCI_INT_DATA_END | SDHCI_INT_RESPONSE |
 		SDHCI_INT_ADMA_ERROR;
 
+	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
+		intmask &= ~(SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT);
+
 	sdhci_writel(host, intmask, SDHCI_INT_ENABLE);
 	sdhci_writel(host, intmask, SDHCI_SIGNAL_ENABLE);
 }
@@ -1684,6 +1687,9 @@ int sdhci_add_host(struct sdhci_host *host)
 	mmc->f_max = host->max_clk;
 	mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_SDIO_IRQ;
 
+	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
+		mmc->caps |= MMC_CAP_NEEDS_POLL;
+
 	if ((caps & SDHCI_CAN_DO_HISPD) ||
 		(host->quirks & SDHCI_QUIRK_FORCE_HIGHSPEED))
 		mmc->caps |= MMC_CAP_SD_HIGHSPEED;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 5a5c119..03f035e 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -227,6 +227,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_FORCE_HIGHSPEED			(1<<14)
 /* Controller does not provide transfer-complete interrupt when not busy */
 #define SDHCI_QUIRK_NO_BUSY_IRQ				(1<<15)
+/* Controller has unreliable card detection */
+#define SDHCI_QUIRK_BROKEN_CARD_DETECTION		(1<<16)
 
 	int			irq;		/* Device IRQ */
 	void __iomem *		ioaddr;		/* Mapped address */
-- 
1.5.6.5