Re: rtl8821ae dbi read question

[Nik Nyby <nikolas@gnu.org>]

On 11/05/2017 11:50 AM, Larry Finger wrote:
> 
> If you read the commit message for commit b8b8b16352cd, you will find 
> that we do not understand why using a byte read causes failure, but 
> reverting the change so that it is a word read made it function again. 
> The "fix" was found by a user doing bisection, and verified on my 
> system, where the RTL8821AE has stable connections. The transfer rates 
> take wild swings, but the connection is not dropped.
> 
> If you NIC behaves differently, then you will need to help us debug the 
> problem. If you had a kernel that worked, then you might try bisection. 

I just tested on kernels 4.12 and 4.13 - my connection gets dropped on 
those kernels as well. Right now I'm using 4.14-rc7.

> If that is not possible, you might try various combinations of module 
> parameters aspm, int_clear, and msi
Thanks for these suggestions. Disabling ASPM solves my connection 
dropping issue! Previously, I was getting disconnected around 10 seconds 
after starting "git clone" on a large git repository. Now, I haven't 
seen the connection drop once.

I can help debug the issue. I'm using a Lenovo Ideapad 320-15ABR laptop. 
Here's the lspci -vv info for my NIC:

01:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8821AE 
802.11ac PCIe Wireless Network Adapter
         Subsystem: Lenovo RTL8821AE 802.11ac PCIe Wireless Network Adapter
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Stepping- SERR- FastB2B- DisINTx+
         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- 
<TAbort- <MAbort- >SERR- <PERR- INTx-
         Latency: 0, Cache Line Size: 32 bytes
         Interrupt: pin A routed to IRQ 33
         Region 0: I/O ports at 2000 [size=256]
         Region 2: Memory at f0b00000 (64-bit, non-prefetchable) [size=16K]
         Capabilities: <access denied>
         Kernel driver in use: rtl8821ae