Re: [RFC PATCH] usb: gadget: composite Allow for larger configuration descriptors

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And here is the actual packet capture that should have been attached in
the last mail


On 26.04.2018 20:26, Joel Pepper wrote:
> I have been doing some work with uvc gadgets, which mirrors the
> capabilities of actual webcams attached to a host port.
> During testing I ran into -EPIPE errors when trying to retrieve
> configurations for more complex devices.
>
> I tracked the errors down to running over the rather conservative
> buffer size of 1024 bytes for config descriptors. This size is
> insufficient when dealing with more realistic uvc gadgets,
> which need around 50 bytes per framesize per format.
> I have attached a packet capture from the setup of a Logitech C270
> (a very common webcam), which sends a config descriptor of 2530 bytes.
>
> I would have liked to go to 8192 immediately, but I have insufficient
> knowledge of the USB spec in general and linux
> and hardware implementations in particular, hence this RFC and the more
> conservative choice of 4096, which allows for a single versatile
> uvc-gadget while leaving headroom for other functions.
>
>
> Joel Pepper (1):
>   usb: gadget: composite Allow for larger configuration descriptors
>
>  include/linux/usb/composite.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Attachment: logitech-c270-conf-desc-only.pcapng
Description: application/pcapng


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