Am Samstag, 1. August 2009 00:01:27 schrieb Sarah Sharp:
> Hi Oliver,
Hello,
> I know you worked on several versions of a mass storage device
> autosuspend patch.
For the discussion I am attaching what I found in my archives.
It is a bit incomplete in hindsight. We should definitely do autopm_get
in the open methods of sg and st.
Be careful they surprised Alan and maybe caused convultions.
Regards
Oliver
--
--- a/drivers/usb/storage/usb.c 2007-09-27 13:33:31.000000000 +0200
+++ b/drivers/usb/storage/usb.c 2007-09-27 13:30:21.000000000 +0200
@@ -182,33 +182,100 @@ static struct us_unusual_dev us_unusual_
static int storage_suspend(struct usb_interface *iface, pm_message_t message)
{
+ struct device *child;
struct us_data *us = usb_get_intfdata(iface);
+ struct Scsi_Host *host = us_to_host(us);
+ struct scsi_device *sdev, *sdev2 = NULL;
+ int err = 0;
+
+ /* In case of autosuspend we need to do extra work to flush
+ * buffers and spin down disks. */
+ if (us->pusb_dev->auto_pm) {
+ US_DEBUGP("Autosuspend code path.\n");
+ /* block all devices against block and user space io */
+ shost_for_each_device(sdev, host) {
+ US_DEBUGP("Quiescing device.\n");
+ err = scsi_device_quiesce(sdev);
+ US_DEBUGP("Quiesced device with result %d.\n", err);
+ if (err < 0) {
+ sdev2 = sdev;
+ err = -EIO;
+ scsi_device_put(sdev);
+ goto err_unblock;
+ }
+ child = &sdev->sdev_gendev;
+ if (!child->driver || !child->driver->suspend)
+ continue;
+ US_DEBUGP("About to suspend disk.\n");
+ /* flush the buffers and spin down */
+ err = (child->driver->suspend)(child, message);
+ if (err < 0) {
+ US_DEBUGP("Could not suspend disk.\n");
+ sdev2 = sdev;
+ shost_for_each_device(sdev, host) {
+ if (sdev == sdev2) {
+ scsi_device_put(sdev);
+ break;
+ }
+ child = &sdev->sdev_gendev;
+ if (!child->driver || !child->driver->resume)
+ continue;
+ (child->driver->resume)(child);
+ }
+ err = -EIO;
+ sdev2 = NULL;
+ scsi_device_put(sdev);
+ goto err_unblock;
+ }
+ }
+ }
+
+ 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;
+
+ /* In case of autosuspend device must be unblocked again */
+ if (us->pusb_dev->auto_pm) {
+err_unblock:
+ shost_for_each_device(sdev, host) {
+ if (sdev == sdev2) {
+ scsi_device_put(sdev);
+ break;
+ }
+ scsi_device_resume(sdev);
+ }
+ }
+ return err;
}
static int storage_resume(struct usb_interface *iface)
{
struct us_data *us = usb_get_intfdata(iface);
+ struct Scsi_Host *host;
+ struct scsi_device *sdev;
+ struct device *child;
- mutex_lock(&us->dev_mutex);
+ if (us->pusb_dev->auto_pm) {
+ host = us_to_host(us);
+ shost_for_each_device(sdev, host) {
+ child = &sdev->sdev_gendev;
+ if (!child->driver || !child->driver->resume)
+ continue;
+ (child->driver->resume)(child);
+ }
+ }
US_DEBUGP("%s\n", __FUNCTION__);
+
if (us->suspend_resume_hook)
(us->suspend_resume_hook)(us, US_RESUME);
- mutex_unlock(&us->dev_mutex);
return 0;
}
@@ -306,6 +373,7 @@ static int usb_stor_control_thread(void
{
struct us_data *us = (struct us_data *)__us;
struct Scsi_Host *host = us_to_host(us);
+ int autopm_rc;
for(;;) {
US_DEBUGP("*** thread sleeping.\n");
@@ -314,6 +382,9 @@ static int usb_stor_control_thread(void
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));
@@ -372,6 +443,12 @@ static int usb_stor_control_thread(void
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));
@@ -414,6 +491,10 @@ 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 */
@@ -931,6 +1012,7 @@ retry:
/* Should we unbind if no devices were detected? */
}
+ usb_autopm_put_interface(us->pusb_intf);
complete_and_exit(&us->scanning_done, 0);
}
@@ -1016,6 +1098,7 @@ 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;
@@ -1053,6 +1136,7 @@ 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)
--- a/drivers/usb/storage/scsiglue.c 2007-09-27 13:33:31.000000000 +0200
+++ b/drivers/usb/storage/scsiglue.c 2007-09-25 13:24:20.000000000 +0200
@@ -285,10 +285,15 @@ 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;
}
--
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