On Wed, Mar 6, 2013 at 8:04 PM, Bjørn Mork <bjorn@xxxxxxx> wrote:
> Ming Lei <ming.lei@xxxxxxxxxxxxx> writes:
>
>> If suspend callback fails in system sleep context, usb core will
>> ignore the failure and let system sleep go ahead further, so
>> this patch doesn't recover device under this situation.
>>
>> Cc: Bjørn Mork <bjorn@xxxxxxx>
>> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
>> ---
>> drivers/net/usb/cdc_mbim.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c
>> index 248d2dc..ec58c2c 100644
>> --- a/drivers/net/usb/cdc_mbim.c
>> +++ b/drivers/net/usb/cdc_mbim.c
>> @@ -338,7 +338,7 @@ static int cdc_mbim_suspend(struct usb_interface *intf, pm_message_t message)
>>
>> if (intf == ctx->control && info->subdriver && info->subdriver->suspend)
>> ret = info->subdriver->suspend(intf, message);
>> - if (ret < 0)
>> + if (ret < 0 && PMSG_IS_AUTO(message))
>> usbnet_resume(intf);
>>
>> error:
>
> This condition will never happen because the subdriver callback always
> return 0 if !PMSG_IS_AUTO(message), so adding anything here is purely
> for documentation purposes. That is OK for me. But I do not see any
> point adding incomplete or wrong documentation.
>
> The above is incomplete because it ignores the failure and still return
> an error. And it is wrong because we ignore an error we cannot possibly
> handle in resume. Only the subdriver can do that, which is why we must
> delegate this to the subdriver.
>
> I believe the correct here is to document the fact that we require the
> subdriver->suspend() callback to always return 0 if !PMSG_IS_AUTO(message).
> That is best done with a comment. No need to add any redundant code.
Considered that the subdriver might change its return value in future, how about
just add the below comment?
/* TODO: resume() might need to handle suspend failure from subdriver */
Thanks,
--
Ming Lei
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