From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aaron Lu Subject: Re: [PATCH v7 4/4] sd: change to auto suspend mode Date: Mon, 21 Jan 2013 20:44:14 +0800 Message-ID: <50FD381E.6040002@intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Alan Stern Cc: Aaron Lu , Jens Axboe , "Rafael J. Wysocki" , James Bottomley , linux-pm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Shane Huang List-Id: linux-pm@vger.kernel.org On 01/19/2013 05:25 AM, Alan Stern wrote: > On Wed, 16 Jan 2013, Aaron Lu wrote: > >> From: Lin Ming >> >> Uses block layer runtime pm helper functions in >> scsi_runtime_suspend/resume. >> Remove scsi_autopm_* from sd open/release path and check_events path. >> And remove the quiesce call in runtime suspend path, as we know there is >> no request to quiesce for the device. >> >> Signed-off-by: Lin Ming >> Signed-off-by: Aaron Lu > >> --- a/drivers/scsi/scsi_sysfs.c >> +++ b/drivers/scsi/scsi_sysfs.c >> @@ -893,6 +893,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev) >> */ >> scsi_autopm_get_device(sdev); >> >> + blk_pm_runtime_init(rq,&sdev->sdev_gendev); >> + >> error = device_add(&sdev->sdev_gendev); >> if (error) { >> sdev_printk(KERN_INFO, sdev, > > Someone just asked about the default autosuspend delay, and I realized > your patch series doesn't set one. Since we don't know the properties > of the disk drive at this point (or even whether the device is a disk > drive), the only safe course is to call > > pm_runtime_set_autosuspend_delay(&sdev->sdev_gendev, -1); > > before calling blk_pm_runtime_init(). Then autosuspends will be > prevented until userspace writes a non-negative value into the device's > control/autosuspend_delay_ms file. OK, that would be safer, thanks for the suggestion. I often set the autosuspend delay before allowing runtime PM for the device, since we forbid it in scsi_sysfs_add_sdev. > > The kerneldoc for blk_pm_runtime_init() should mention that the caller > needs to set the autosuspend delay beforehand. OK. Thanks, Aaron