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Subject[PATCH 03/10] 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>
---
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 0f5037d..5a7a584 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -157,6 +157,9 @@ 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, SDHCI_INT_ENABLE, intmask);
sdhci_writel(host, SDHCI_SIGNAL_ENABLE, intmask);
}
@@ -1677,6 +1680,9 @@ 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 fed0022..f357722 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -213,6 +213,8 @@ 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


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