Small follow-up: I'm refering to GMAC send/receive clock delay chain. For 
Banana Pi/Pro it was necessary to set bit 10-12 of the gmac clk register to 3 
to get decent network throughput (for Cubietruck it's set to 1 currently). 

http://lists.denx.de/pipermail/u-boot/2014-September/190239.html

This is done in u-boot:

http://lists.denx.de/pipermail/u-boot/2015-January/202590.html

Since this is a very board specific value to compensate for trace lengths on 
the PCB (see explanation above) I had doubts that using also 3 on the Lamobo R1 
(which has a totally different PCB and uses a different PHY than Banana Pi/Pro) 
would make any sense. Igor tried a few other values (2,4,5,6,7,9,12) and came 
up with 4 giving better results. So now he sets "CONFIG_GMAC_TX_DELAY=4"

https://github.com/igorpecovnik/lib/blob/next/patch/add-lamobo-r1-uboot.patch

If I have the time I will set up an unattended test setup and brute-force 
through all possible values of CONFIG_GMAC_TX_DELAY and also 
CONFIG_GMAC_RX_DELAY (why shouldn't the other direction not also be affected? 
This is what we have right now with all A20 boards: asymmetric throughput).

With mainline kernel and adjusted SMP, network and cpufreq settings (also due 
to patched U-boot) I managed to get 940 Mbits/sec RX and 670 Mbits/sec TX: 
http://forum.lemaker.org/thread-12167-1-1-nas_performance_with_kernel_3_19_0.html

This is what I want to achieve on the Lamobo R1 as well and try to reach 940 
Mbits/sec TX on Banana Pi/Pro. But no idea whether the idea to set 
CONFIG_GMAC_RX_DELAY will work since code for this value in board/sunxi/gmac.c 
seems to be missing (and unfortunately I'm no coder)

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