Re: [PATCH] brcmfmac: support monitor frames with hardware/ucode header

[Arend Van Spriel <arend.vanspriel@broadcom.com>]

On 1/25/2019 10:11 AM, Rafał Miłecki wrote:
> On 2019-01-25 09:51, Arend Van Spriel wrote:
>> On 1/22/2019 12:08 PM, Rafał Miłecki wrote:
>>> From: Rafał Miłecki <rafal@milecki.pl>
>>>
>>> The new FullMAC firmwares for 4366b1/4366c0 were supposed to provide
>>> monitor frames with radiotap header but it doesn't seem to be the case.
>>
>> I was not aware that this was supposed to. I did not build a radiotap
>> variant to keep it feature-wise similar to 4366b0 firmware.
> 
> Well, then apparently I got confused :( When you wrote:
> 
> On Mon, 11 Jun 2018 at 12:48, Arend van Spriel 
> <arend.vanspriel@broadcom.com> wrote:
>> Looking into our firmware repo it there are two flags, ie. WL_MONITOR
>> and WL_RADIOTAP. It seems both are set for firmware containing -stamon-
>> feature. Your list below confirms that. I still plan to add indication
>> for WL_RADIOTAP in the "cap" iovar, but a stamon feature check could be
>> used for older firmwares.
> 
> I assumed you'll add "rtap" cap value (to the internal wl code repository?)
> because you mean to release a firmware using it.
> 
> Maybe you just meant it to be for your customers compiling firmwares on
> their own?

and for customer for whom we compile firmwares based on their feature 
requirements. Anyway, I could build a new firmware for 4366b1/4366c0 
including radiotap. However, end-users may get to use firmware that is 
not supporting it.

>>> Testing the latest release resulted in discovering a new format being
>>> used. It seems (almost?) identical to the one known from ucode used in
>>> SoftMAC devices which is most likely the same codebase anyway.
>>
>> I am a bit confused. How many formats are there? It is either ucode
>> format or radiotap, right?
> 
> So far we got two formats:
> 1) 802.11 frames (with frame (sub)type & all addresses)
> 2) 802.11 frames with the radiotap header
> and now we also have:
> 3) 802.11 frames with the ucode header
> 
> For more info please check my original post:
> Research + questions on brcmfmac and support for monitor mode
> https://www.spinics.net/lists/linux-wireless/msg173573.html

I did read that before, but apparently did miss some details.

>>> While radiotap support was meant to be announced with the "rtap" fw
>>> capability string it seems no alternative was added for the hw/ucode
>>> format. It means each firmware requires a feature mapping quirk.
>>
>> I thought we only needed a quirk for the firmware that provide
>> radiotap but do not announce it. For the others we can assume ucode
>> format if monitor mode is supported. Probably missing something.
> 
> 802.11 frames with ucode header is something entirely new, I didn't see any
> Asus/Linksys/Netgear/TP-LINK firmware using it.
> 
> As the old firmwares were providing frames without any header (also making
> it impossible to e.g. read signal strength) we need this new flag to
> distinguish firmwares with ucode header from them.

Right. Thanks for explaining (again).

Regards,
Arend