Re: [PATCH] rtlwifi: rtl8821ae: Fix connection lost problem correctly

Larry Finger [off-list ref] writes:

There has been a coding error in rtl8821ae since it was first introduced,
namely that an 8-bit register was read using a 16-bit read in
_rtl8821ae_dbi_read(). This error was fixed with commit 40b368af4b75
("rtlwifi: Fix alignment issues"); however, this change led to
instability in the connection. To restore stability, this change
was reverted in commit b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection
lost problem").

Unfortunately, the unaligned access causes machine checks in ARM
architecture, and we were finally forced to find the actual cause of the
problem on x86 platforms. Following a suggestion from Pkshih
[off-list ref], it was found that increasing the ASPM L1
latency from 0 to 7 fixed the instability. This parameter was varied to
see if a smaller value would work; however, it appears that 7 is the
safest value. A new symbol is defined for this quantity, thus it can be
easily changed if necessary.

Fixes: b8b8b16352cd ("rtlwifi: rtl8821ae: Fix connection lost problem")
Cc: Stable <redacted> # 4.14+
Fix-suggested-by: Pkshih [off-list ref]
Signed-off-by: Larry Finger <redacted>
---

Kalle,

This patch should be submitted to 4.16.

Ok, I'll queue this to 4.16.

-- 
Kalle Valo