On Sat, 2 Feb 2013, Aaron Lu wrote: > >> An alternative way of possibly solving this problem from PM's point of > >> view might be: > >> 1 Set both ata port and scsi device's runtime status to RPM_SUSPENDED > >> in their system suspend callback; By the way, what reason is there for doing this to the ATA port? Does the port take a long time to resume, in the same way that a disk can take a few seconds to spin back up? > >> 2 On resume, do nothing in their system resume callback; > >> 3 With request based runtime PM introduced here: > >> http://thread.gmane.org/gmane.linux.power-management.general/30405 > >> When a request comes for the HDD after system resume, both the ata > >> port and the scsi device will be runtime resumed, which involves > >> re-initialize the ata link(in ata port's runtime resume callback) and > >> spin up the HDD(in sd's runtime resume callback). > >> > >> To make HDD un-affetcted by runtime PM during normal use, a large enough > >> autosuspend_delay can be set for it. > >> > >> Just my 2 cents, I've not verified or tried in any way yet :-) > > > > It's a good idea. The problem is that it won't work if CONFIG_PM_SLEEP > > is enabled but CONFIG_PM_RUNTIME isn't. > > Right, what a pity... thanks for the hint. > > But the code is really simple if we ignore this problem(with some proper > modifications to scsi bus PM callbacks, see the delayed_resume branch if > you are interested), so I'm tempted to post it here :-) > > drivers/ata/libata-core.c | 22 +++++++++++----------- > drivers/scsi/scsi_pm.c | 14 +++++++++++--- > 2 files changed, 22 insertions(+), 14 deletions(-) > > diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c > index 497adea..38000fc 100644 > --- a/drivers/ata/libata-core.c > +++ b/drivers/ata/libata-core.c > @@ -5355,10 +5355,19 @@ static int ata_port_suspend_common(struct device *dev, pm_message_t mesg) > > static int ata_port_suspend(struct device *dev) > { > + int ret; > + > if (pm_runtime_suspended(dev)) > return 0; > > - return ata_port_suspend_common(dev, PMSG_SUSPEND); > + ret = ata_port_suspend_common(dev, PMSG_SUSPEND); > + if (!ret) { > + __pm_runtime_disable(dev, false); Don't you mean pm_runtime_disable(dev)? > + pm_runtime_set_suspended(dev); > + pm_runtime_enable(dev); > + } > + > + return ret; > } > > static int ata_port_do_freeze(struct device *dev) > @@ -5393,16 +5402,7 @@ static int ata_port_resume_common(struct device *dev, pm_message_t mesg) > > static int ata_port_resume(struct device *dev) > { > - int rc; > - > - rc = ata_port_resume_common(dev, PMSG_RESUME); > - if (!rc) { > - pm_runtime_disable(dev); > - pm_runtime_set_active(dev); > - pm_runtime_enable(dev); > - } > - > - return rc; > + return 0; > } > > /* > diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c > index d9956b6..d0b6997 100644 > --- a/drivers/scsi/scsi_pm.c > +++ b/drivers/scsi/scsi_pm.c > @@ -127,13 +127,21 @@ static int scsi_bus_prepare(struct device *dev) > static int scsi_bus_suspend(struct device *dev) > { > const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; > - return scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL); > + int ret; > + > + ret = scsi_bus_suspend_common(dev, pm ? pm->suspend : NULL); > + if (!ret) { > + __pm_runtime_disable(dev, false); > + pm_runtime_set_suspended(dev); > + pm_runtime_enable(dev); > + } > + > + return ret; > } > > static int scsi_bus_resume(struct device *dev) > { > - const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL; > - return scsi_bus_resume_common(dev, pm ? pm->resume : NULL); > + return 0; > } This doesn't look like it would work very well with something like a CD drive, which doesn't use block-layer runtime PM. Is that what you meant when you talked about modifying the SCSI PM callbacks? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
