Adrian Hunter wrote:
On 3/01/2012 12:33 p.m., Ulf Hansson wrote:
Removing a card "slowly" can trigger a GPIO irq to be raised far
before the card is actually removed. This means the scheduled
detect work will not find out that the card were removed and thus
the card and the block device will not be unregistered.
One way around that problem is to error out requests after the GPIO
indicates the card is "removed". sdhci effectively does that but with
a "present" bit. Perhaps even simpler - set the card-removed flag.
I get the idea, but that will only partly solve this issue.
My concern is more about what we actually can trust; either the GPIO irq
which likely is giving more than one irq when inserting/removing a card
since the slot is probably not glitch free, or that a "rescan" runs to
make sure a CMD13 is accepted from the previously inserted card.
Moreover, the issue this patch tries to solve can not be solved without
doing a "rescan" which must be triggered from the the block layer some
how. I thought this new function that you previously added
"mmc_detect_card_remove" was the proper place to do this.
Let the mmc_detect_card_removed function trigger a new detect
work immediately when it discovers that a card has been removed.
This is changing some long-standing functionality i.e. the card is not
removed
without a card detect event. It is difficult to know whether that will
be very
bad for poor quality cards,
Doing a mmc_detect (rescan) will in the end just issue a CMD13 to the
card to make sure it is still present, that is already done from the
block layer after each read/write request. So I can not see that "poor
quality cards" will have any further problem with this patch, but I
might miss something!?
This will solve the described issue above. Moreover we make sure
the detect work is executed as soon as possible, since there is
no reason for waiting for a "delayed" detect to happen.
Signed-off-by: Ulf Hansson<ulf.hansson@xxxxxxxxxxxxxx>
---
drivers/mmc/core/core.c | 24 +++++++++++++-----------
include/linux/mmc/host.h | 1 -
2 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 4770807..7bc02f4 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1462,7 +1462,6 @@ void mmc_detect_change(struct mmc_host *host, unsigned long delay)
WARN_ON(host->removed);
spin_unlock_irqrestore(&host->lock, flags);
#endif
- host->detect_change = 1;
mmc_schedule_delayed_work(&host->detect, delay);
}
@@ -2077,18 +2076,23 @@ int _mmc_detect_card_removed(struct mmc_host *host)
int mmc_detect_card_removed(struct mmc_host *host)
{
struct mmc_card *card = host->card;
+ int ret = 1;
WARN_ON(!host->claimed);
- /*
- * The card will be considered unchanged unless we have been asked to
- * detect a change or host requires polling to provide card detection.
- */
- if (card&& !host->detect_change&& !(host->caps& MMC_CAP_NEEDS_POLL))
- return mmc_card_removed(card);
- host->detect_change = 0;
+ if (card&& !mmc_card_removed(card)) {
+ if (_mmc_detect_card_removed(host)) {
+ /*
+ * Make sure a detect work is always executed and also
+ * do it as soon as possible.
+ */
+ cancel_delayed_work(&host->detect);
+ mmc_detect_change(host, 0);
+ }
+ ret = mmc_card_removed(card);
+ }
- return _mmc_detect_card_removed(host);
+ return ret;
}
EXPORT_SYMBOL(mmc_detect_card_removed);
@@ -2112,8 +2116,6 @@ void mmc_rescan(struct work_struct *work)
&& !(host->caps& MMC_CAP_NONREMOVABLE))
host->bus_ops->detect(host);
- host->detect_change = 0;
-
/*
* Let mmc_bus_put() free the bus/bus_ops if we've found that
* the card is no longer present.
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 031d865..09fa5e6 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -305,7 +305,6 @@ struct mmc_host {
int claim_cnt; /* "claim" nesting count */
struct delayed_work detect;
- int detect_change; /* card detect flag */
struct mmc_hotplug hotplug;
const struct mmc_bus_ops *bus_ops; /* current bus driver */
Br
Ulf Hansson
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