Oliver Neukum <oliver@xxxxxxxxxx> writes:
> Am Montag, 30. Januar 2012, 19:26:17 schrieb Bjørn Mork:
>> Oliver Neukum <oliver@xxxxxxxxxx> writes:
>>
>> > Bjørn, in this case it is best to provide two helping function
>> > pointers when you create the "subdevice" and realize the counters
>> > in the network driver.
>>
>> Do you mean to let the cdc-wdm subdriver call back the main driver when
>> it wants to set/clear the needs_remote_wakeup flag?
>
> Yes.
>
>> Yes, I can do that but I sort of feel it messes up the interface for
>> little gain. We'd need to store the callback pointers and modify
>> wdm_open and wdm_release to use them conditionally. Or provide local
>> callbacks for use as a normal driver. Not pretty at all.
>
> Providing local alternatives is pretty clean. probe() can pass them to create()
>
>> I am currently leaning towards just documenting that cdc-wdm will change
>> the needs_remote_wakeup flag and that any driver using cdc-wdm as a
>> subdriver therefore will have to prevent autosuspending while being
>> active. This can be done without involving neither usb core nor
>
> We want devices to be able to autosuspend as often as possible.
Good. I will add something like that. But does it really need to be
two functions, or can we use something similar to usbnet's
"manage_power" (which does the same thing)? It is defined as
/* (dis)activate runtime power management */
int (*manage_power)(struct usbnet *, int);
where the second argument really is a bool telling if we need remote
wakeup or not, thereby combining get/put (or on/off) in a single
callback. The cdc_ether implementation demostrates the usage:
static int cdc_manage_power(struct usbnet *dev, int on)
{
dev->intf->needs_remote_wakeup = on;
return 0;
}
Having two separate on/off functions wouldn't add anything but
complexity. I believe the same goes for the cdc-wdm case.
Bjørn
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