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Subject[PATCH 1/3] mmc: add support for card-detection polling
Some hosts (and boards that use mmc_spi) do not use interrupts on the CD
line, so they can't trigger mmc_detect_change. We want to poll the card
and see if there was a change. 1 second poll interval seems resonable.

This patch also implements .get_cd() host operation, that could be used
by the hosts that are able to report card-detect status without need to
talk MMC.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
---
drivers/mmc/core/core.c | 12 +++++++++---
include/linux/mmc/host.h | 11 +++++++++++
2 files changed, 20 insertions(+), 3 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 01ced4c..ede5d1e 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -638,6 +638,9 @@ void mmc_rescan(struct work_struct *work)
*/
mmc_bus_put(host);

+ if (host->ops->get_cd && host->ops->get_cd(host) == 0)
+ goto out;
+
mmc_claim_host(host);

mmc_power_up(host);
@@ -652,7 +655,7 @@ void mmc_rescan(struct work_struct *work)
if (!err) {
if (mmc_attach_sdio(host, ocr))
mmc_power_off(host);
- return;
+ goto out;
}

/*
@@ -662,7 +665,7 @@ void mmc_rescan(struct work_struct *work)
if (!err) {
if (mmc_attach_sd(host, ocr))
mmc_power_off(host);
- return;
+ goto out;
}

/*
@@ -672,7 +675,7 @@ void mmc_rescan(struct work_struct *work)
if (!err) {
if (mmc_attach_mmc(host, ocr))
mmc_power_off(host);
- return;
+ goto out;
}

mmc_release_host(host);
@@ -683,6 +686,9 @@ void mmc_rescan(struct work_struct *work)

mmc_bus_put(host);
}
+out:
+ if (host->caps & MMC_CAP_NEEDS_POLL)
+ mmc_schedule_delayed_work(&host->detect, HZ);
}

void mmc_start_host(struct mmc_host *host)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 7ab962f..6188e19 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -51,8 +51,18 @@ struct mmc_ios {

struct mmc_host_ops {
void (*request)(struct mmc_host *host, struct mmc_request *req);
+ /*
+ * Avoid calling these three functions too often or in a "fast path",
+ * since underlaying controller might implement them in an expensive
+ * and/or slow way.
+ *
+ * Also note that these functions might sleep, so don't call them
+ * in the atomic contexts!
+ */
void (*set_ios)(struct mmc_host *host, struct mmc_ios *ios);
int (*get_ro)(struct mmc_host *host);
+ int (*get_cd)(struct mmc_host *host);
+
void (*enable_sdio_irq)(struct mmc_host *host, int enable);
};

@@ -94,6 +104,7 @@ struct mmc_host {
#define MMC_CAP_SD_HIGHSPEED (1 << 3) /* Can do SD high-speed timing */
#define MMC_CAP_SDIO_IRQ (1 << 4) /* Can signal pending SDIO IRQs */
#define MMC_CAP_SPI (1 << 5) /* Talks only SPI protocols */
+#define MMC_CAP_NEEDS_POLL (1 << 6) /* Needs polling for card-detection */

/* host specific block data */
unsigned int max_seg_size; /* see blk_queue_max_segment_size */
--
1.5.5.4


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