Re: [PATCH v2] usb: gadget: f_midi: fixed a bug when buflen was smaller than wMaxPacketSize

From	Felipe Balbi <balbi@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] usb: gadget: f_midi: fixed a bug when buflen was smaller than wMaxPacketSize
Date	2016-03-29 12:40 +0200
Message-ID	<rhZe2-4MC-11@gated-at.bofh.it> (permalink)
References	<rfUsa-6E2-27@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi,

"Felipe F. Tonello" <eu@felipetonello.com> writes:
> [ text/plain ]
> buflen by default (256) is smaller than wMaxPacketSize (512) in high-speed
> devices.
>
> That caused the OUT endpoint to freeze if the host send any data packet of
> length greater than 256 bytes.
>
> This is an example dump of what happended on that enpoint:
> HOST:   [DATA][Length=260][...]
> DEVICE: [NAK]
> HOST:   [PING]
> DEVICE: [NAK]
> HOST:   [PING]
> DEVICE: [NAK]
> ...
> HOST:   [PING]
> DEVICE: [NAK]
>
> Users should not change the buffer size to anything other than wMaxPacketSize
> because that can cause bugs (this bug) or performance issues. Thus, this patch
> fixes this problem by eliminating buflen entirely and replacing it with
> wMaxPacketSize of the appropriate endpoint where needed.
>
> Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
> ---
>
> v2:
>  - Removed buflen

sounds like removing buflen should be delyed to v4.7 merge window while
the fix is, indeed, needed. Can you drop the removal of buflen ? I guess
it's mostly about picking v1 and fixing endianess problems ?

-- 
balbi

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[PATCH v2] usb: gadget: f_midi: fixed a bug when buflen was smaller than wMaxPacketSize "Felipe F. Tonello" <eu@felipetonello.com> - 2016-03-23 18:10 +0100
  Re: [PATCH v2] usb: gadget: f_midi: fixed a bug when buflen was smaller than wMaxPacketSize Michal Nazarewicz <mina86@mina86.com> - 2016-03-28 16:50 +0200
  Re: [PATCH v2] usb: gadget: f_midi: fixed a bug when buflen was smaller than wMaxPacketSize Felipe Balbi <balbi@kernel.org> - 2016-03-29 12:40 +0200

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