Re: [PATCH] arm64: dts: rockchip: improve rk3328-roc-cc rgmii performance.

[Peter Geis <pgwipeout@gmail.com>]

On 6/14/2019 5:27 PM, Leonidas P. Papadakos wrote:
> 
> 
>> The big change was actually snps,aal.
>> As per the TRM, DMA channels not address aligned have severe
>> limitations, if they work at all.
>>
>> Setting the DMA ops as address aligned fixed my 30mbps TX issue when
>> combined with your snps,txpbl = <0x4>.
> 
> Honestly, I don't notice any difference either way with aal. So what 
> happens without it? If You only use the 0x4 txpbl and having removed 
> thresh dma mode, (2 things then) do you get bad tx?
> 
> 

I'm unsure why, but I think there might be small variations in the 
different boards (Firefly, Libre).
On my board (Libre) with just 0x4 txpbl and thresh dma removed I get a 
whopping 30mbps.

Adding aal brought it up to 900 mbps.

I also had stability issues on rx, where it would bounce between 200 and 
400 mbps, which adding 0x4 rxpbl helped.
I still haven't been able to get rx above 400mpbs though.

It's definitely the MTU issue, since setting the max mtu to 1496 fixes 
most problems.

I have to wonder if the pl330 in the rk3328 is bugged, since all of the 
hardware that misbehaves (usb3, mmc, rgmii) require the dma engine.

If this works as a valid replacement for thresh dma mode, then I can 
submit it for merging.
I would like a few more people to test it first.

Anyone else with a rk3328-roc-cc board that can test this patch?