Re: [PATCH 1/2] usb: gadget: introduce flag for large request

From: Alan Stern
Date: Tue Jun 16 2020 - 10:02:50 EST


On Tue, Jun 16, 2020 at 08:34:43PM +0800, Macpaul Lin wrote:
> Some USB hardware like DMA engine can help to process (split) the data
> of each URB request into small packets. For example, the max packet size
> of high speed is 512 bytes. These kinds of hardware can help to split
> the continue Tx/Rx data requests into packets just at the max packet
> size during transmission. Hence upper layer software can reduce some
> effort for queueing many requests back and forth for larger data.
>
> Here we introduce "can_exceed_maxp" flag in gadget when these kinds of
> hardware is ready to support these operations.

This isn't needed. All UDC drivers must be able to support requests that
are larger than the maxpacket size.

Alan Stern