Re: [PATCH 1/1] TX throttling bug-fixing patch of AX88179_178A

Ming Lei
2013-07-25T05:25:12Z

On Thu, Jul 25, 2013 at 1:10 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2013-07-25 at 10:28 +0800, Ming Lei wrote:
>
>>
>> It depends if size of sg buffer(except for last one) in the sg list can be
>> divided by usb endpoint's max packet size(512 or 1024), at least there
>> is the constraint:
>>
>> http://git.kernel.org/cgit/linux/kernel/git/gregkh/usb.git/commit/?h=usb-next&id=10e232c597ac757e7f8600649f7e872e86de190f
>>
>> I am wondering if network stack can meet that. If not, it might be a
>> bit difficult
>> because lots of USB host controller don't support that, and driver may have
>> to support SG and non-SG at the same time for working well on all HCs.
>
> I do not see the problem.
>
> If one skb has 2 fragments of 32KB, couldn't they be split into 64 1K
> segments by the device driver ?

OK, if length of fragments of all SKBs from network stack can always guarantee
to be divided by 1024, that is fine, seems I worry about too much, :-)

Thanks,
--
Ming Lei