mmc: mmc_rescan detects card change in one run

With this patch, mmc_rescan can detect the removal of an mmc card and
the insertion of (possibly another) card in the same run. This means
that a card change can be detected without having to call
mmc_detect_change multiple times.

This change generalises the core such that it can be easily used by
hosts which provide a mechanism to detect only the presence of a card
reader cover, which has to be taken off in order to insert a card. Other
hosts ("card detect" or "MMC_CAP_NEEDS_POLL") each receive an event when
a card is removed and when a card is inserted, so it is sufficient for
them if mmc_rescan handles only one event at a time. "Cover detect"
hosts, however, only receive events about the cover status. This means
that between 2 subsequent events, both a card removal and a card
insertion can occur. In this case, the pre-patch version of mmc_rescan
would only detect the removal of the previous card but not the insertion
of the new card.

Signed-off-by: Jorg Schummer <ext-jorg.2.schummer@nokia.com>
Signed-off-by: Pierre Ossman <pierre@ossman.eu>

1 files changed, 55 insertions, 44 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 264911732756..23fb2c39d9ed 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -855,61 +855,72 @@ void mmc_rescan(struct work_struct *work)
 
         mmc_bus_get(host);
 
-        if (host->bus_ops == NULL) {
-                /*
-                 * Only we can add a new handler, so it's safe to
-                 * release the lock here.
-                 */
+        /* if there is a card registered, check whether it is still present */
+        if ((host->bus_ops != NULL) && host->bus_ops->detect && !host->bus_dead)
+                host->bus_ops->detect(host);
+
+        mmc_bus_put(host);
+
+
+        mmc_bus_get(host);
+
+        /* if there still is a card present, stop here */
+        if (host->bus_ops != NULL) {
                 mmc_bus_put(host);
+                goto out;
+        }
 
-                if (host->ops->get_cd && host->ops->get_cd(host) == 0)
-                        goto out;
+        /* detect a newly inserted card */
 
-                mmc_claim_host(host);
+        /*
+         * Only we can add a new handler, so it's safe to
+         * release the lock here.
+         */
+        mmc_bus_put(host);
 
-                mmc_power_up(host);
-                mmc_go_idle(host);
+        if (host->ops->get_cd && host->ops->get_cd(host) == 0)
+                goto out;
 
-                mmc_send_if_cond(host, host->ocr_avail);
+        mmc_claim_host(host);
 
-                /*
-                 * First we search for SDIO...
-                 */
-                err = mmc_send_io_op_cond(host, 0, &ocr);
-                if (!err) {
-                        if (mmc_attach_sdio(host, ocr))
-                                mmc_power_off(host);
-                        goto out;
-                }
+        mmc_power_up(host);
+        mmc_go_idle(host);
 
-                /*
-                 * ...then normal SD...
-                 */
-                err = mmc_send_app_op_cond(host, 0, &ocr);
-                if (!err) {
-                        if (mmc_attach_sd(host, ocr))
-                                mmc_power_off(host);
-                        goto out;
-                }
+        mmc_send_if_cond(host, host->ocr_avail);
 
-                /*
-                 * ...and finally MMC.
-                 */
-                err = mmc_send_op_cond(host, 0, &ocr);
-                if (!err) {
-                        if (mmc_attach_mmc(host, ocr))
-                                mmc_power_off(host);
-                        goto out;
-                }
+        /*
+         * First we search for SDIO...
+         */
+        err = mmc_send_io_op_cond(host, 0, &ocr);
+        if (!err) {
+                if (mmc_attach_sdio(host, ocr))
+                        mmc_power_off(host);
+                goto out;
+        }
 
-                mmc_release_host(host);
-                mmc_power_off(host);
-        } else {
-                if (host->bus_ops->detect && !host->bus_dead)
-                        host->bus_ops->detect(host);
+        /*
+         * ...then normal SD...
+         */
+        err = mmc_send_app_op_cond(host, 0, &ocr);
+        if (!err) {
+                if (mmc_attach_sd(host, ocr))
+                        mmc_power_off(host);
+                goto out;
+        }
 
-                mmc_bus_put(host);
+        /*
+         * ...and finally MMC.
+         */
+        err = mmc_send_op_cond(host, 0, &ocr);
+        if (!err) {
+                if (mmc_attach_mmc(host, ocr))
+                        mmc_power_off(host);
+                goto out;
         }
+
+        mmc_release_host(host);
+        mmc_power_off(host);
+
 out:
         if (host->caps & MMC_CAP_NEEDS_POLL)
                 mmc_schedule_delayed_work(&host->detect, HZ);