PM / Hibernate: Add resumewait param to support MMC-like devices as resume file

Some devices like MMC are async detected very slow. For example,
drivers/mmc/host/sdhci.c launches a 200ms delayed work to detect
MMC partitions then add disk.

We have wait_for_device_probe() and scsi_complete_async_scans()
before calling swsusp_check(), but it is not enough to wait for MMC.

This patch adds resumewait kernel param just like rootwait so
that we have enough time to wait until MMC is ready. The difference is
that we wait for resume partition whereas rootwait waits for rootfs
partition (which may be on a different device).

This patch will make hibernation support many embedded products
without SCSI devices, but with devices like MMC.

[rjw: Modified the changelog slightly.]

Signed-off-by: Barry Song <Baohua.Song@csr.com>
Reviewed-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 854ed5ca7e3f122f5ac808b462eb14b9ee6b1977..88a7b197a4eb538446fb04cfa718448dad90c0c2 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2240,6 +2240,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        in <PAGE_SIZE> units (needed only for swap files).
                        See  Documentation/power/swsusp-and-swap-files.txt
 
+       resumewait      [HIBERNATION] Wait (indefinitely) for resume device to show up.
+                       Useful for devices that are detected asynchronously
+                       (e.g. USB and MMC devices).
+
        hibernate=      [HIBERNATION]
                noresume        Don't check if there's a hibernation image
                                present during boot.

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 7f44e5c269712a96c582f177df5152c19603e996..0f8785080cde7b75162b2d302cc179811172aaf4 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -14,6 +14,7 @@
 #include <linux/reboot.h>
 #include <linux/string.h>
 #include <linux/device.h>
+#include <linux/async.h>
 #include <linux/kmod.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
@@ -31,6 +32,7 @@
 
 static int nocompress = 0;
 static int noresume = 0;
+static int resume_wait = 0;
 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
 dev_t swsusp_resume_device;
 sector_t swsusp_resume_block;
@@ -736,6 +738,13 @@ static int software_resume(void)
                 * to wait for this to finish.
                 */
                wait_for_device_probe();
+
+               if (resume_wait) {
+                       while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
+                               msleep(10);
+                       async_synchronize_full();
+               }
+
                /*
                 * We can't depend on SCSI devices being available after loading
                 * one of their modules until scsi_complete_async_scans() is
@@ -1064,7 +1073,14 @@ static int __init noresume_setup(char *str)
        return 1;
 }
 
+static int __init resumewait_setup(char *str)
+{
+       resume_wait = 1;
+       return 1;
+}
+
 __setup("noresume", noresume_setup);
 __setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
 __setup("hibernate=", hibernate_setup);
+__setup("resumewait", resumewait_setup);