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

Anton Vorontsov
2009-03-16T21:14:53Z

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 | 17 +++++++++++++++--
drivers/mmc/host/sdhci.h | 2 ++
2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6fbbc00..fc7cb48 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 a9e25c6..968d713 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 */
--
1.5.6.5