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

Alan Stern [off-list ref] 於 2020年6月16日 週二 下午10:05寫道：

On Tue, Jun 16, 2020 at 08:34:43PM +0800, Macpaul Lin wrote:

quoted

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

Thanks for your reply, could we just modify the patch 2 (u_serial.c)
for improving
better performance? I'm not sure why there was a restriction about max packet.
Isn't there any historical reason?

-- 
Best regards,
Macpaul Lin

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