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>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 2649117..23fb2c3 100644 (file)
--- 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);