mmc: core: Prevent too long response times for suspend

While trying to suspend the mmc host there could still be
ongoing requests that we need to wait for. At the same time
a device driver must respond to a suspend request rather quickly.

Instead of potentially wait "forever" by claiming the host we now
"try" to claim the host instead. If it fails, -EBUSY is returned.

Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Reviewed-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 27 insertions, 15 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index fe65bb377e2..5278ffb20e7 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2294,21 +2294,33 @@ int mmc_suspend_host(struct mmc_host *host)
 
         mmc_bus_get(host);
         if (host->bus_ops && !host->bus_dead) {
-                if (host->bus_ops->suspend)
-                        err = host->bus_ops->suspend(host);
-                if (err == -ENOSYS || !host->bus_ops->resume) {
-                        /*
-                         * We simply "remove" the card in this case.
-                         * It will be redetected on resume.
-                         */
-                        if (host->bus_ops->remove)
-                                host->bus_ops->remove(host);
-                        mmc_claim_host(host);
-                        mmc_detach_bus(host);
-                        mmc_power_off(host);
-                        mmc_release_host(host);
-                        host->pm_flags = 0;
-                        err = 0;
+
+                /*
+                 * A long response time is not acceptable for device drivers
+                 * when doing suspend. Prevent mmc_claim_host in the suspend
+                 * sequence, to potentially wait "forever" by trying to
+                 * pre-claim the host.
+                 */
+                if (mmc_try_claim_host(host)) {
+                        if (host->bus_ops->suspend)
+                                err = host->bus_ops->suspend(host);
+                        if (err == -ENOSYS || !host->bus_ops->resume) {
+                                /*
+                                 * We simply "remove" the card in this case.
+                                 * It will be redetected on resume.
+                                 */
+                                if (host->bus_ops->remove)
+                                        host->bus_ops->remove(host);
+                                mmc_claim_host(host);
+                                mmc_detach_bus(host);
+                                mmc_power_off(host);
+                                mmc_release_host(host);
+                                host->pm_flags = 0;
+                                err = 0;
+                        }
+                        mmc_do_release_host(host);
+                } else {
+                        err = -EBUSY;
                 }
         }
         mmc_bus_put(host);