WLAN connection: 5 GHz priority

[solitone <solitone@mail.com>]

Although this issue is widely discussed, but I didn't find a way to solve it. 
My access point provides both 2.4 GHz and 5 GHz bands, and I'd like my WiFi 
adapter chose 5 GHz over 2.4.

To accomplish this, I reduced the AP's TX power for 2.4 GHz, and increased 
that for 5 GHz. The point is that when the 2.4 GHz signal is higher than 5 
GHz, my WiFi adapter prefers the 2.4 channel, even though usually the 5 GHz 
channel is less crowded and has less interference and therefore its 
performance would likely be better.

Another way would be to configure two separate SSIDs, one for 2.4 GHz, the 
other for 5 GHz. However, neither option is viable when I have no control on 
the APs, like in a university wireless campus.

Is there some tweak I can do on the kernel module, so that the choice doesn't 
rely on any specific configuration on the AP?

My laptop features a Broadcom BCM43602 802.11ac WiFi adapter, supported by the 
brcmfmac driver:

$ sudo lspci -vnn |grep BCM43602 -A17
03:00.0 Network controller [0280]: Broadcom Limited BCM43602 802.11ac Wireless 
LAN SoC [14e4:43ba] (rev 01)
        Subsystem: Apple Inc. BCM43602 802.11ac Wireless LAN SoC [106b:0133]
        Flags: bus master, fast devsel, latency 0, IRQ 55
        Memory at c1400000 (64-bit, non-prefetchable) [size=32K]
        Memory at c1000000 (64-bit, non-prefetchable) [size=4M]
        Capabilities: [48] Power Management version 3
        Capabilities: [58] MSI: Enable+ Count=1/16 Maskable- 64bit+
        Capabilities: [68] Vendor Specific Information: Len=44 <?>
        Capabilities: [ac] Express Endpoint, MSI 00
        Capabilities: [100] Advanced Error Reporting
        Capabilities: [13c] Device Serial Number 0f-bd-a7-ff-ff-9d-98-01
        Capabilities: [150] Power Budgeting <?>
        Capabilities: [160] Virtual Channel
        Capabilities: [1b0] Latency Tolerance Reporting
        Capabilities: [220] #15
        Capabilities: [240] L1 PM Substates
        Kernel driver in use: brcmfmac
        Kernel modules: brcmfmac

I found this patch that seems relevant:
brcmfmac: Give priority to 5GHz band in selecting target BSS
https://patchwork.kernel.org/patch/4156831/

but it seems it wasn't ever applied.
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