[OpenWrt-Devel] Announcement of mac80211 driver support for Marvell 88W8864 chip

Ian Kent raven at themaw.net
Sat Jan 24 04:37:18 EST 2015

On Mon, 2015-01-12 at 19:03 -0800, David Lin wrote:
> Hi Ian,
> 	1. I will take off these additional blank lines.
> 	2. I work for problems reported from community. If you do find problems for the driver, please let me know.

Hi David,

I was disappointed to find that client mode wireless in the driver isn't
supported yet.

I logged an issue for it at https://github.com/kaloz/mwlwifi/issues/13
along with the kernel WARN() info.

As I say in the issue I believe that client mode is quite important for
the coming WRT1200AC, assuming the wireless on that device is to be
supported by this driver.

I've been looking at the driver source and I'm a bit puzzled about the
rate and ht_sig2 fields in the receive descriptor structure. There's no
documentation (that I can locate) on the interface to the wireless
device so I can't refer to it.

It appears the rate field isn't just a rate or an index into the rate
table or just an MCS rate either. So can you describe what the encoding
is please?

The ht_sig2 field has a describing comment of "as the name suggests" but
HT SIG 2 is 24 bits not 16 and even if the CRC and tail fields were
discarded, I see there's more than the remaining 10 bits being used in
the field. So can you describe the encoding in this field too please?

The other puzzling thing is the handling of VHT modes.
I don't see anything in the receive descriptor for that case.
It looks like the wireless device handles the rate (along with a lot
more) but how does the driver find out the VHT information that it may
need for informational and reporting purposes (up to the mac80211

Could you help with this please.

These questions may sound like I don't know low level wireless concepts
and that would be correct, but I'm slowly working on that, so sorry for
the possibly silly questions.

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