usb-storage: implement autosuspend

This patch (as930) implements autosuspend for usb-storage.  It is
adapted from a patch by Oliver Neukum.  Autosuspend is allowed except
during LUN scanning, resets, and command execution.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 29 insertions, 11 deletions

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 1ba19eaa1970..47e56079925d 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -285,10 +285,15 @@ static int device_reset(struct scsi_cmnd *srb)
 
         US_DEBUGP("%s called\n", __FUNCTION__);
 
-        /* lock the device pointers and do the reset */
-        mutex_lock(&(us->dev_mutex));
-        result = us->transport_reset(us);
-        mutex_unlock(&us->dev_mutex);
+        result = usb_autopm_get_interface(us->pusb_intf);
+        if (result == 0) {
+
+                /* lock the device pointers and do the reset */
+                mutex_lock(&(us->dev_mutex));
+                result = us->transport_reset(us);
+                mutex_unlock(&us->dev_mutex);
+                usb_autopm_put_interface(us->pusb_intf);
+        }
 
         return result < 0 ? FAILED : SUCCESS;
 }
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index cf3fc91234e7..bef8bcd9bd98 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -191,16 +191,14 @@ static int storage_suspend(struct usb_interface *iface, pm_message_t message)
 {
         struct us_data *us = usb_get_intfdata(iface);
 
+        US_DEBUGP("%s\n", __FUNCTION__);
+
         /* Wait until no command is running */
         mutex_lock(&us->dev_mutex);
 
-        US_DEBUGP("%s\n", __FUNCTION__);
         if (us->suspend_resume_hook)
                 (us->suspend_resume_hook)(us, US_SUSPEND);
 
-        /* When runtime PM is working, we'll set a flag to indicate
-         * whether we should autoresume when a SCSI request arrives. */
-
         mutex_unlock(&us->dev_mutex);
         return 0;
 }
@@ -209,13 +207,11 @@ static int storage_resume(struct usb_interface *iface)
 {
         struct us_data *us = usb_get_intfdata(iface);
 
-        mutex_lock(&us->dev_mutex);
-
         US_DEBUGP("%s\n", __FUNCTION__);
+
         if (us->suspend_resume_hook)
                 (us->suspend_resume_hook)(us, US_RESUME);
 
-        mutex_unlock(&us->dev_mutex);
         return 0;
 }
 
@@ -313,6 +309,7 @@ static int usb_stor_control_thread(void * __us)
 {
         struct us_data *us = (struct us_data *)__us;
         struct Scsi_Host *host = us_to_host(us);
+        int autopm_rc;
 
         current->flags |= PF_NOFREEZE;
 
@@ -323,6 +320,9 @@ static int usb_stor_control_thread(void * __us)
                         
                 US_DEBUGP("*** thread awakened.\n");
 
+                /* Autoresume the device */
+                autopm_rc = usb_autopm_get_interface(us->pusb_intf);
+
                 /* lock the device pointers */
                 mutex_lock(&(us->dev_mutex));
 
@@ -381,6 +381,12 @@ static int usb_stor_control_thread(void * __us)
                         us->srb->result = SAM_STAT_GOOD;
                 }
 
+                /* Did the autoresume fail? */
+                else if (autopm_rc < 0) {
+                        US_DEBUGP("Could not wake device\n");
+                        us->srb->result = DID_ERROR << 16;
+                }
+
                 /* we've got a command, let's do it! */
                 else {
                         US_DEBUG(usb_stor_show_command(us->srb));
@@ -423,6 +429,10 @@ SkipForAbort:
 
                 /* unlock the device pointers */
                 mutex_unlock(&us->dev_mutex);
+
+                /* Start an autosuspend */
+                if (autopm_rc == 0)
+                        usb_autopm_put_interface(us->pusb_intf);
         } /* for (;;) */
 
         /* Wait until we are told to stop */
@@ -939,6 +949,7 @@ retry:
         }
 
         scsi_host_put(us_to_host(us));
+        usb_autopm_put_interface(us->pusb_intf);
         complete_and_exit(&threads_gone, 0);
 }
 
@@ -1028,6 +1039,7 @@ static int storage_probe(struct usb_interface *intf,
          * start it up. */
         scsi_host_get(us_to_host(us));
         atomic_inc(&total_threads);
+        usb_autopm_get_interface(intf); /* dropped in the scanning thread */
         wake_up_process(th);
 
         return 0;
@@ -1065,6 +1077,7 @@ static struct usb_driver usb_storage_driver = {
         .pre_reset =    storage_pre_reset,
         .post_reset =   storage_post_reset,
         .id_table =     storage_usb_ids,
+        .supports_autosuspend = 1,
 };
 
 static int __init usb_stor_init(void)