[PATCH 07/12] wifi: mt76: mt7996: set correct beamformee SS capability

[Shayne Chen (陳軒丞)]

On Mon, 2024-08-19 at 07:22 -0700, Ben Greear wrote:
>  	 
> External email : Please do not click links or open attachments until
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>  On 8/16/24 02:46, Shayne Chen wrote:
> > From: Howard Hsu <howard-yh.hsu at mediatek.com>
> > 
> > According to IEEE P802.11be/D6.0 Table 9-417n, beamformee SS field
> stands
> > for the maximum number of spatial streams that the STA can receive
> in an
> > EHT sounding NDP minus 1, and the minimum value of this field is 3.
> > 
> > This value indicates the decoding capability of a beamformee, which
> is
> > independent of current antenna settings. Correct the value for
> mt7996
> > and mt7992 chipsets based on their HW capability.
> 
> I thought that if user sets a specific number of antennas, the code
> should
> act as if that were the number of physical antennas, so this change
> seems
> wrong to me.
> 
We used to think that this field depends on the antennas. However, we
see that IEEE spec defines the minimum value of this field is 3, so we
think what the field means is the "MAX HW decoding capability", no
matter how many antennas that user currently configured.

For example, if user configures a beamformee with only 1 antenna, it is
still abled to decode a "(RX)-1x4-(TX)" matrix from a beamformer. 

> What use-case is this patch attempting to fix?
> 
We faced issues when doing some BF performance and cert tests.

Thanks,
Shayne

> Thanks,
> Ben
>