This patch implements autosuspend and autoresume for usb-storage. It
is based on the SCSI Dynamic PM patch just posted on linux-scsi and
linux-pm.
Note: For testing, you will have to set the power/level attribute (and
possibly also power/autosuspend) for both the SCSI device and the USB
device.
Alan Stern
Index: usb-2.6/drivers/usb/storage/usb.c
===================================================================
--- usb-2.6.orig/drivers/usb/storage/usb.c
+++ usb-2.6/drivers/usb/storage/usb.c
@@ -184,16 +184,14 @@ static int storage_suspend(struct usb_in
{
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;
}
@@ -202,13 +200,10 @@ static int storage_resume(struct usb_int
{
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;
}
@@ -928,6 +923,7 @@ static int usb_stor_scan_thread(void * _
/* Should we unbind if no devices were detected? */
}
+ usb_autopm_put_interface(us->pusb_intf);
complete_and_exit(&us->scanning_done, 0);
}
@@ -957,6 +953,9 @@ static int storage_probe(struct usb_inte
return -ENOMEM;
}
+ /* Don't autosuspend until the SCSI core tells us */
+ usb_autopm_get_interface(intf);
+
/*
* Allow 16-byte CDBs and thus > 2TB
*/
@@ -1017,6 +1016,7 @@ static int storage_probe(struct usb_inte
goto BadDevice;
}
+ usb_autopm_get_interface(intf); /* dropped in the scanning thread */
wake_up_process(th);
return 0;
@@ -1054,6 +1054,7 @@ static struct usb_driver usb_storage_dri
.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)
Index: usb-2.6/drivers/usb/storage/scsiglue.c
===================================================================
--- usb-2.6.orig/drivers/usb/storage/scsiglue.c
+++ usb-2.6/drivers/usb/storage/scsiglue.c
@@ -295,10 +295,15 @@ static int device_reset(struct scsi_cmnd
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;
}
@@ -341,6 +346,24 @@ void usb_stor_report_bus_reset(struct us
scsi_unlock(host);
}
+/* The host and its devices are all idle so we can autosuspend */
+static int autosuspend(struct Scsi_Host *host)
+{
+ struct us_data *us = host_to_us(host);
+
+ usb_autopm_put_interface(us->pusb_intf);
+ return 0;
+}
+
+/* The host needs to be autoresumed */
+static int autoresume(struct Scsi_Host *host)
+{
+ struct us_data *us = host_to_us(host);
+
+ return usb_autopm_get_interface(us->pusb_intf);
+}
+
+
/***********************************************************************
* /proc/scsi/ functions
***********************************************************************/
@@ -467,6 +490,10 @@ struct scsi_host_template usb_stor_host_
.eh_device_reset_handler = device_reset,
.eh_bus_reset_handler = bus_reset,
+ /* dynamic power management */
+ .autosuspend = autosuspend,
+ .autoresume = autoresume,
+
/* queue commands only, only one command per LUN */
.can_queue = 1,
.cmd_per_lun = 1,
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