August 18, 2018

U-Boot network for the NanoPi Fire3 - progress as of 8-18-2018

It is 8-18-2018. I began all of this U-Boot work on 8-10-2018. After investing almost all of my free time for the better part of a week, it is worth taking stock.

Things I have learned

There exists something that looks like the very driver that I need - drivers/net/designware.c

The most recent thing I did, which yielded significant progress, was to find the code that does the clock control for the ethernet GMAC and run it, after that I actually see what looks like action from the network, but get an Exception: 

nanopi3# dhcp
tjt: dw_eth_init: d2:a5:61:c9:2e:e4
In dw_write_hwaddr: d2:a5:61:c9:2e:e4 (tjt)
Speed: 1000, full duplex
BOOTP broadcast 1
"Synchronous Abort" handler, esr 0x96000061
ELR:     7da8bb20
LR:      7da8bb0c
x0 : 0000000000060101 x1 : 000000007daedc30
x2 : 0000000000000006 x3 : 0000000000000006
x4 : 000000007daedc86 x5 : 00000000000000e4
x6 : 00000000000000bd x7 : 000000007daee270
x8 : 0000000000000000 x9 : 0000000039e3b000
x10: 000000007ba36562 x11: 00000000ffffffff
x12: 00000000ffffffff x13: 000000007da9fdc0
x14: 0000000000000001 x15: 000000007ba38800
x16: 0000000000000005 x17: 0000000000000004
x18: 000000007ba36df8 x19: 000000007daedc8e
x20: 000000007daedc8e x21: 000000000000000e
x22: 000000007daef000 x23: 000000007daed000
x24: 0000000000000001 x25: 000000007daef000
x26: 000000007daefadc x27: 0000000000000000
x28: 000000007ba38b30 x29: 000000007ba36a30

Resetting CPU ...
The speed looks right (I am plugged into a 1000 Mbit switch), which hints that the Phy stuff is working as it should. I wonder if a packet ever gets sent. If I use a 100 Mbit switch, I wonder if it will see that, or is 1000 Mbit just a lucky accident?

I dig out an ancient 10-base-T hub. Plugged into that I get: 

nanopi3# dhcp
tjt: dw_eth_init: d2:a5:61:c9:2e:e4
In dw_write_hwaddr: d2:a5:61:c9:2e:e4 (tjt)
dwmac.c0060000 Waiting for PHY auto negotiation to complete..... done
Speed: 10, half duplex
BOOTP broadcast 1
"Synchronous Abort" handler, esr 0x96000061
So it looks like the Phy information is the real thing!!

This makes me wonder about my inability to blink a GPIO. I try to set the alt function register of the GPIO to "1" for the GMAC lines so it will function as a GMAC rather than GPIO. Maybe this is the reset behavior anyway -- I don't see code for this anywhere, and I would expect it right alongside the GMAC clock stuff.

Unsolved questions and research topics

The Artik 710 uses the s5p6818 and it looks like it gets configured to work with the designware driver. I build this and try it on the Fire3 and all I get is the following message and a boot loop. It seems like this ought to "just work". What is wrong? The following is the same message (coming from bl1_mmcboot.bin) that I get from my nanopi3 build. 
Launch to 0x7FD00800
Then there is a research topic -- how exactly does the boot scheme on the s5p6818 work. Why is there fip_secure.img as well as fip_loader.img and bl1_mmcboot.bin. What is all of this about?

Why is U-Boot linked to run at 0x43C00000, but seems to run at addresses like 0x7da8bb20? In fact I confirmed this by writing some code that prints the address it is running at: 

I am at 7da3dc44

Why am I unable to control the GPIO from simple C code in U-Boot? Do I need to fiddle with reset bit? I can find no clock control for the GPIO. A quick experiment with the GPIO reset bits at 0xc0010208 yielded no improvement.

Have any comments? Questions? Drop me a line!

Tom's electronics pages / [email protected]