Comment 6 for bug 1069766

One important note about support for BCM4331 (specifically for the PHY it uses) is that it is reverse-engineered and very much suboptimal and incomplete. 802.11n support is completely missing.

I did some tests on a Macbook Pro 8,2 with iperf and got similar numbers for TCP download. My upload speeds were comparable to the download speeds, which doesn't match your results. I don't really know what can be done to fix it though; we really just don't know how to properly configure the hardware. Broadcom indicated at one point that they have plans to support BCM4331 in brcmsmac, but there's been no indication of when this might happen.