hi alan
2015-05-06 2:32 GMT+08:00 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>:
> On Wed, 6 May 2015, yoma sophian wrote:
>
>> hi all:
>> below are call back functions of usb_storage_driver:
>> static struct usb_driver usb_storage_driver = {
>> .name = "usb-storage",
>> .probe = storage_probe,
>> .disconnect = usb_stor_disconnect,
>> .suspend = usb_stor_suspend,
>> .resume = usb_stor_resume,
>> .reset_resume = usb_stor_reset_resume,
>> .pre_reset = usb_stor_pre_reset,
>> .post_reset = usb_stor_post_reset,
>> .id_table = usb_storage_usb_ids,
>> .supports_autosuspend = 1,
>> .soft_unbind = 1,
>> };
>>
>> my questions are:
>> 1. where we register the us->suspend_resume_hook in usb_stor_suspend?
>> I grep the src, but cannot find where the callback is registered.
>
> The callback can be registered between the calls to usb_stor_probe1()
> and usb_stor_probe2().
I neither find suspend_resume_hook registered in probe1 or probe2.
in probe1, we do following initialization:
mutex_init(&(us->dev_mutex));
us_set_lock_class(&us->dev_mutex, intf);
init_completion(&us->cmnd_ready);
init_completion(&(us->notify));
init_waitqueue_head(&us->delay_wait);
get_transport(us);
get_protocol(us);
in probe2, we acquire us_data related resources and register host to
scsi layer.
result = usb_stor_acquire_resources(us);
result = scsi_add_host(us_to_host(us), dev);
it seems we didn't register suspend_resume_hook.
>
>> 2. suppose we are doing the scsi read/write command and system
>> suddenly store to RAM/DISK, will that scsi command do?
>> Drop it or keep the unfinished part ?
>
> It will wait until the SCSI command is finished and then invoke your
> callback routine.
so you mean if we are doing CBW, in/out date and CSW, once hibernate
happen during the end of CBW, kernel will wait CSW finished then go to
hibernate?
in the resume case, we will port reset device and re-enumerate storage device.
if so, shouldn't we free previous resource allocated before hibernate?
appreciate your kind help,
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