Oliver Neukum <oneukum@xxxxxxx> writes:
> On Monday 21 January 2013 15:47:13 Bjørn Mork wrote:
>> But I wonder if this isn't really a generic problem in usbnet. The
>> FLAG_MULTI_PACKET test here seems completely bogus:
>>
>> if (length % dev->maxpacket == 0) {
>> if (!(info->flags & FLAG_SEND_ZLP)) {
>> if (!(info->flags & FLAG_MULTI_PACKET)) {
>> urb->transfer_buffer_length++;
>> if (skb_tailroom(skb)) {
>> skb->data[skb->len] = 0;
>> __skb_put(skb, 1);
>> }
>> }
>> } else
>> urb->transfer_flags |= URB_ZERO_PACKET;
>> }
>>
>> Either the FLAG_MULTI_PACKET minidriver will have already padded the
>> buffer so that we do not hit (length % dev->maxpacket == 0), or we
>> should choose one of the alternatives: ZLP or padding.
>
> But we cannot simply call __skb_put for a complicated data frame.
Agreed. But I believe the condition should be
if (!(info->flags & FLAG_SEND_ZLP) && !(info->flags & FLAG_MULTI_PACKET)) {
..
} else {
urb->transfer_flags |= URB_ZERO_PACKET;
}
to ensure that we send the ZLP in this case.
> Besides you may want the current behavior.
Why? Does it ever make sense to prevent both the short packet and the
ZLP?
Bjørn
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