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points by edg5000 2 days ago | 0 comments

The CM4 and Pi 4 use the Cypress CYW43455 for Wi-FI, which I found to be unreliable. Under load, it crashes, and it can't be fixed in the kernel.

Frustratingly, many other SoMs and SBCs use this chip. I don't understand why there is no recall on this - in my opinion - trash product. It's an odd feeling to be the only one experiencing this. I am 100% confident this is a design flaw in the CYW43455. I've seen this also on a Pine64 CM4 compatible SoM, which has a completely different SoC. This is on both the official and custom carrier. Cypress, fix your shit!

[–] numpad0 2 days ago

Qualcomm did it once. A SAW filter had hermetic seal issue or something and Wi-Fi modems lost voice in matters of months. Quite a lot of Android phones around 2010-2012 were affected. Virtually none of manufacturers took actions based on that information.

[–] userbinator 2 days ago

I believe that is actually a Broadcom chip, originally BCM43455.

[–] edg5000 2 days ago

It's the same chip, renamed (which is silly) after the Broadcom IoT division was bought by Cypress, which is bought by Infineon. So technically, it's the Infineon CYW43455 (formerly Broadcom BCM43455).

https://www.infineon.com/part/CYW43455

[–] lp92 1 day ago

It'spossible it's thermal limits are being triggered. Many years ago I had a laptop that started dropping WiFi when it got too hot. Fixed it with some copper shims and thermal tape.

[–] mrheosuper 2 days ago

While the SoC maybe different, the FW on the Wireless SOC could be similar.

[–] edg5000 2 days ago

Yes, so different SoC, same WiFi, same issues, isolating the issues to the WiFi chip (common denominator). Carrier was also ruled out since I tried a custom and Raspberry offical one.

[–] mrheosuper 2 days ago

No, i mean the problem could be in the Wireless FW, not Wireless chip, which mean it can be patched.

[–] edg5000 1 day ago

I wonder how feasible decompilation is. The firmware is used in many boards. An open, cleanroom reimplementation (derriving hardware details from the firmware, then reimplementing cleanly in embedded C++ or rust) could fix the issues, that would be very interesting.

[–] mrheosuper 1 day ago

It's feasible, in fact i'm in process of decompiling a bluetooth blob from other vendor. But the thing is it's just Bluetooth, Wifi is vastly more complex than BT.

[–] userbinator 2 hours ago

Wifi is vastly more complex than BT

I disagree; BT is several orders of magnitude more complex, since it includes many more layers than Wifi (which is really just a physical layer for carrying Ethernet).