Re: [PATCH v1 1/3] usb: gadget: NCM: RX function support multiple NDPs

Jim Baxter [off-list ref] writes:

The NDP was ignoring the wNextNdpIndex in the NDP which
means that NTBs containing multiple NDPs would have missed
frames.

Well, just for the record: I believe this field was meant to be reserved
and always 0 in the CDC NCM spec.  Table 3-3, describing 16bit NDPs,
says so.  But reading the spec now, I noticed that there is an
inconsistency between table 3-3 and table 3-4 describing 32bit NDPs.  It
looks like the field is not reserved in the 32bit version.

I am pretty sure that is a specification error, but I guess it doesn't
harm to implement the support anyway.  And it paves the way for an MBIM
gadget :-)




Bjørn

On 29/05/14 19:55, Bjørn Mork wrote:

Jim Baxter [off-list ref] writes:

quoted

The NDP was ignoring the wNextNdpIndex in the NDP which
means that NTBs containing multiple NDPs would have missed
frames.

Well, just for the record: I believe this field was meant to be reserved
and always 0 in the CDC NCM spec.  Table 3-3, describing 16bit NDPs,
says so.  But reading the spec now, I noticed that there is an
inconsistency between table 3-3 and table 3-4 describing 32bit NDPs.  It
looks like the field is not reserved in the 32bit version.

I am pretty sure that is a specification error, but I guess it doesn't
harm to implement the support anyway.  And it paves the way for an MBIM
gadget :-)




Bjørn

Yes I was looking at Figure 3-1, Figure 3-2 which all state it is a
link. I must have been reading Table 3-4.

I am glad to see it helps with the MBIM specification :-) .

Jim