[U-Boot] [PATCH 00/35][RFC] arm: socfpga: Usability fixes

Wed Sep 17 13:07:29 CEST 2014

On Wed, 2014-09-17 at 01:52 +0200, marex at denx.de wrote:
> On Wednesday, September 17, 2014 at 12:29:54 AM, Dinh Nguyen wrote:
> 
> [...]
> 
> > >> Yes, tracked it down to get_ram_size(). I forced gd->ram_size to 1GB and
> > >> it works fine for me now. I'll try to spend some cycles to debug the
> > >> problem.
> > > 
> > > Hmmmmm, how much DRAM can the SoCFPGA chip drive in total ?
> > 
> > All of our devkits have at least 1 GiB and I have heard there is a
> > variant with 2GiB in the wild. Spec says up to 4 GiB.
> 
> OK, I see. You cannot realistically map all those 4GiB into the 32-bit address 
> space of an CortexA9, but on the other hand, all those bugs related to an CA9 
> with 4GiB of DRAM should be fixed due to my work on Novena ;-)

Yup, 4GB would not be possible. Within SocFPGA, by using HPS-FPGA
bridges, we can workaround by swapping memory chunk so ARM processor can
access entire 4GB. Interested to find out how you did it for Novena :)

> 
> > > Well, consider a theoretical SoCFPGA board with 128MiB of DRAM attached
> > > to it, what happens if I try to write at address of the 129th MiB (which
> > > is past the DRAM) ? Will this generate an DABT for the ARM core or will
> > > some kind of DRAM "mirroring" or "wraparound" happen such that I would
> > > write to the content of 1st MiB of the DRAM ?
> > 
> > We've encountered this issue downstream on a system with 1 GiB.
> 
> OK, so a wraparound happens ?
> 

It should be a wrap around. It is not working previously as incorrect
configuration for one of SDRAM parameters. The fix is under internal
review now. :)

> > > If I would get DABT, then there is a rather easy fix for that, see
> > > arch/arm/cpu/arm926ejs/mxs/spl_mem_init.c and mxs_mem_get_size()
> > > function. The function places an assembly return instruction into the
> > > DABT handler entry position (offset 0x14 in ARM vector table IIRC) and
> > > then runs the get_dram_size() . The assembly instruction only returns
> > > from the DABT handler right past the code where the DABT happened. For
> > > the get_ram_size(), the read from the unpopulated DRAM space contains
> > > zeroes and the function doesn't even realize the DABT happened. But it
> > > considers the DRAM invalid and thus this works correctly. That's how it
> > > detects the amount of DRAM.
> > > 
> > > You might want to consider something similar if that's how it behaves on
> > > SoCFPGA.
> > 
> > This could be the issue. I think Chin Liang would know about this more
> > than me at this point. So I hope he can solve this quickly.
> 
> Sure, patch is welcome!
> 

Hmmm... actually I can get it works well for my Altera dev kit. The
get_dram_size would take in the argument PHYS_SDRAM_1_SIZE. From here,
the function will ensure the memory specified can read and writable. If
its failing here, probably the SDRAM access might have issue. FYI,
PHYS_SDRAM_1_SIZE is 0x40000000 for 1GB.

> > Seems odd that the get_ram_size is working on your DENX board and not
> > the devkit.
> 
> I _think_ I might have hacked this part up and it's still in the cleanup 
> pipeline.
> 

It works for me without hacks. I can read and write to the SDRAM memory
well (include 1MB region).

U-Boot 2014.10-rc2-00123-g461be2f-dirty (Sep 17 2014 - 04:28:52)

CPU:   Altera SoCFPGA Platform
BOARD: Altera SoCFPGA Cyclone5 Board
DRAM:  1 GiB
WARNING: Caches not enabled
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   dwmac.ff702000
Error: dwmac.ff702000 address not set.

Warning: Your board does not use generic board. Please read
doc/README.generic-board and take action. Boards not
upgraded by the late 2014 may break or be removed.
Hit any key to stop autoboot:  0
Wrong Image Format for bootm command
ERROR: can't get kernel image!
SOCFPGA_CYCLONE5 # md 0
00000000: 00000000 aaaaaaaa aaaaaaaa aaaaaaaa    ................
00000010: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa    ................
00000020: 55555555 55555555 55555555 55555555    UUUUUUUUUUUUUUUU
00000030: 55555555 55555555 55555555 55555555    UUUUUUUUUUUUUUUU
00000040: 7f7b958a a30289de 6bfe35cb 2d3f494f    ..{......5.kOI?-
00000050: d5777778 6f010bb3 ec671fe4 27131f7b    xww....o..g.{..'
00000060: 2f6ff6e4 bb97cecd 7fff9dda 6ffa1fcd    ..o/...........o
00000070: b7375b84 7159d3ae f07ac971 e99bbff6    .[7...Yqq.z.....
00000080: d325d7fd d3b663b8 f377cfea f3675f72    ..%..c....w.r_g.
00000090: 3d1d4cd9 11a59b18 b795fffd 33ba95b8    .L.=...........3
000000a0: 575bbfef 73eb794f 33536eee 104389cf    ..[WOy.s.nS3..C.
000000b0: 7763a778 35ff5fd8 f33e57c1 f777fbce    x.cw._.5.W>...w.
000000c0: f35b6f9b 5bf70fdb bb730de3 7d7b5f88    .o[....[..s.._{}
000000d0: 5547a7f9 f33f07eb a395364c b35377e8    ..GU..?.L6...wS.
000000e0: 77bf6597 27737ea2 af3577f5 5b34f7d9    .e.w.~s'.w5...4[
000000f0: 33eadbba fed7df87 3efbfaa8 83b9ef9c    ...3.......>....
SOCFPGA_CYCLONE5 # mw 0 12345678 100
SOCFPGA_CYCLONE5 # md 0
00000000: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000010: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000020: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000030: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000040: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000050: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000060: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000070: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000080: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
00000090: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000a0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000b0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000c0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000d0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000e0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
000000f0: 12345678 12345678 12345678 12345678    xV4.xV4.xV4.xV4.
SOCFPGA_CYCLONE5 # md 100000
00100000: eafffffd fbff4b3f fffffffe fdff33be    ....?K.......3..
00100010: ffb2aacf f7779ac4 f73bbf7f f7fbfbfc    ......w...;.....
00100020: ffe3bb6d ef9f3fff fdb63bbd f6f76f5d    m....?...;..]o..
00100030: efafbdf1 bbefbdbd efbffcfd fffffffd    ................
00100040: fffbb58f e7baabfc ebfa37cd ed3ff96e    .........7..n.?.
00100050: ff7ff7f4 ef1b3ff3 eff71fb6 ffbb0d73    .....?......s...
00100060: efeff6e7 ffb7afeb f7bfbdfb efffffff    ................
00100070: f7fff7ff f7df73ee f1fafff5 ebbbb1e7    .....s..........
00100080: f3e3dff5 f7eff3ff fb77fd64 fbffdff2    ........d.w.....
00100090: ffbc5cfd f5fbbff8 effffffd f7f8a1fc    .\..............
001000a0: 5b7b3fff f7bb734f fbffffee f3fb8bcf    .?{[Os..........
001000b0: f3b3b75f ffffffda f3bf5fc5 fbffffdb    _........_......
001000c0: f3df6fde dbffffdd fbf1ede7 bd7b7fdc    .o............{.
001000d0: f7d7b77f f39f2fef f7933bdc f35337af    ...../...;...7S.
001000e0: f7f71ddf e7f77e38 ef7777fd ffb4f2fc    ....8~...ww.....
001000f0: f3eafb5e fffffee7 fffbdaec f3f0e5f7    ^...............
SOCFPGA_CYCLONE5 # mw 100000 23456789 100
SOCFPGA_CYCLONE5 # md 100000
00100000: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100010: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100020: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100030: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100040: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100050: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100060: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100070: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100080: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
00100090: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000a0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000b0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000c0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000d0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000e0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
001000f0: 23456789 23456789 23456789 23456789    .gE#.gE#.gE#.gE#
SOCFPGA_CYCLONE5 #

Thanks
Chin Liang

> Best regards,
> Marek Vasut