Am Donnerstag, 12. Januar 2012, 22:50:14 schrieb Sarah Sharp:
> The problem is that since the BMC actually attaches to the host
> controller, it can impact system power management if all the emulated
> devices aren't suspended. A couple of Intel server vendors have gotten
> really cranky about the power management on systems with the EHCI rate
> matching hub and a BMC. Apparently power management is much worse for
> unsuspended HIDs under EHCI than under UHCI, since the EHCI periodic
> frame list keeps getting polled by the EHCI hardware, making the CPU
> come out of C states, etc. Async endpoints don't cause as big a power
> draw, but it would benefit system power management overall if they were
> able to be suspended.
I sense a volunteer tester.
>From 827e677b7127dff9738cf18aed4a426d8e5ca494 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Fri, 13 Jan 2012 08:27:51 +0100
Subject: [PATCH] SCSI:implement PM for sr
This implements basic power management for SCSI disks.
Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
---
drivers/scsi/sr.c | 28 ++++++++++++++++++++++++++--
1 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 5fc97d2..1a21540 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -508,16 +508,29 @@ static int sr_prep_fn(struct request_queue *q, struct request *rq)
static int sr_block_open(struct block_device *bdev, fmode_t mode)
{
+ struct scsi_device *sdev;
struct scsi_cd *cd;
int ret = -ENXIO;
+ int err;
mutex_lock(&sr_mutex);
cd = scsi_cd_get(bdev->bd_disk);
+ sdev = cd->device;
+
+ err = scsi_autopm_get_device(sdev);
+ if (err) {
+ ret = -EIO;
+ goto err_out;
+ }
+
if (cd) {
ret = cdrom_open(&cd->cdi, bdev, mode);
- if (ret)
+ if (ret) {
scsi_cd_put(cd);
+ scsi_autopm_put_device(sdev);
+ }
}
+err_out:
mutex_unlock(&sr_mutex);
return ret;
}
@@ -525,9 +538,12 @@ static int sr_block_open(struct block_device *bdev, fmode_t mode)
static int sr_block_release(struct gendisk *disk, fmode_t mode)
{
struct scsi_cd *cd = scsi_cd(disk);
+ struct scsi_device *sdev = cd->device;
+
mutex_lock(&sr_mutex);
cdrom_release(&cd->cdi, mode);
scsi_cd_put(cd);
+ scsi_autopm_put_device(sdev);
mutex_unlock(&sr_mutex);
return 0;
}
@@ -615,6 +631,11 @@ static int sr_open(struct cdrom_device_info *cdi, int purpose)
struct scsi_device *sdev = cd->device;
int retval;
+ retval = scsi_autopm_get_device(sdev);
+ if (retval) {
+ retval = -EIO;
+ goto pm_error_out;
+ }
/*
* If the device is in error recovery, wait until it is done.
* If the device is offline, then disallow any access to it.
@@ -626,16 +647,19 @@ static int sr_open(struct cdrom_device_info *cdi, int purpose)
return 0;
error_out:
+ scsi_autopm_put_device(sdev);
+pm_error_out:
return retval;
}
static void sr_release(struct cdrom_device_info *cdi)
{
struct scsi_cd *cd = cdi->handle;
+ struct scsi_device *sdev = cd->device;
if (cd->device->sector_size > 2048)
sr_set_blocklength(cd, 2048);
-
+ scsi_autopm_put_device(sdev);
}
static int sr_probe(struct device *dev)
--
1.7.1
--
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