On 11/26/2012 08:50 AM, Rafael J. Wysocki wrote: > On Tuesday, November 20, 2012 04:59:57 PM Aaron Lu wrote: >> On 11/20/2012 02:00 PM, Aaron Lu wrote: >>> On 11/19/2012 10:56 PM, Tejun Heo wrote: >>>> I really think we need a way for (auto)pm and event polling to talk to >>>> each other so that autopm can tell event poll to sod off while pm is >>>> in effect. Trying to solve this from inside libata doesn't seem >>>> right. The problem, again, seems to be figuring out which hardware >>>> device maps to which block device. Hmmm... Any good ideas? >>> >>> A possible way of doing this is using pm qos. >>> >>> We currently have 2 pm qos flags, NO_POWER_OFF and REMOTE_WAKEUP, and we >>> can add another one: NO_POLL, use it like the following: >>> 1 Set the NO_POLL pm qos flag when the underlying driver thinks it is no >>> longer necessary. In the ZPODD's case, it should be set when the >>> device is to be powered off; >>> 2 Clear it when poll is necessary again. In the ZPODD's case, when power >>> is re-gained, this flag will be cleared. >> >> >>> 3 In the disk_events_workfn, check if this flag is set, if so, simply >>> return. >> >> It should be, skip calling disk->fops->check_events, but still queue the >> work for next time's poll. >> >> -Aaron >> >>> >>> The disk->driverfs_dev can be used to host the pm qos flag, ATA layer >>> can access it through ata_device->sdev->sdev_gendev. >>> >>> Is this OK? > > No, I don't think so. PM QoS is about telling the layer that will put the > device into low-power states what states are to be taken into consideration. > In this case, however, we need to tell someone else that the device has been > turned off. Clearly, we need a way to do that, but not through PM QoS. > > Did you consider using pm_runtime_suspended() to check the device status? The problem is, a device can be in runtime suspended state while still needs to be polled... Thanks, Aaron > > Rafael > > -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
