Re: [PATCH v2 0/2] Add macb support for SiFive FU540-C000

[Alistair Francis <Alistair.Francis@wdc.com>]

On Mon, 2019-06-17 at 09:14 -0500, Troy Benjegerdes wrote:
> > On Jun 17, 2019, at 6:34 AM, Paul Walmsley <
> > paul.walmsley@sifive.com> wrote:
> > 
> > On Mon, 17 Jun 2019, Andreas Schwab wrote:
> > 
> > > On Jun 17 2019, Paul Walmsley <paul.walmsley@sifive.com> wrote:
> > > 
> > > > On Mon, 17 Jun 2019, Andreas Schwab wrote:
> > > > 
> > > > > On Jun 17 2019, Paul Walmsley <paul.walmsley@sifive.com>
> > > > > wrote:
> > > > > 
> > > > > > Looks to me that it shouldn't have an impact unless the DT
> > > > > > string is 
> > > > > > present, and even then, the impact might simply be that the
> > > > > > MACB driver 
> > > > > > may not work?
> > > > > 
> > > > > If the macb driver doesn't work you have an unusable system,
> > > > > of course.
> > > > 
> > > > Why?
> > > 
> > > Because a system is useless without network.
> > 
> > From an upstream Linux point of view, Yash's patches should be an 
> > improvement over the current mainline kernel situation, since
> > there's 
> > currently no upstream support for the (SiFive-specific) TX clock
> > switch 
> > register.  With the right DT data, and a bootloader that handles
> > the PHY 
> > reset, I think networking should work after his patches are
> > upstream -- 
> > although I myself haven't tried this yet.
> > 
> 
> Have we documented this tx clock switch register in something with a
> direct URL link (rather than a PDF)?
> 
> I’d like to update freedom-u-sdk (or yocto) to create bootable images
> with a working U-boot (upstream or not, I don’t care, as long as it
> works),
> and what I have right now is the old legacy HiFive U-boot[1] and a
> 4.19
> kernel with a bunch of extra patches.

Yocto/OpenEmbedded does this today. TFTP boot works with the 2019.04 U-
Boot (+ some patches ontop for SMP support). We use the latest 5.1
stable kernel plus 5 or so patches to boot on the Unleased. Networking,
display and audio are all working with the Microsemi expansion board as
well. Let me know if there is something else missing and I'll add it
in. There are probably documentation fixes that are needed as well.

I was thinking of skipping the 5.2 release though as I thought the DT
stuff wasn't going to make it [1]. I will probably re-evaluate that
decision though when 5.2 comes out as it looks like it's all going to
work :)

With U-boot 2017.09 and Linux 5.2/5.3 we should finally be upstream
only!

> 
> The legacy M-mode U-boot handles the phy reset already, and I’ve been
> able to load upstream S-mode uboot as a payload via TFTP, and then 
> load and boot a 4.19 kernel. 
> 
> It would be nice to get this all working with 5.x, however there are
> still
> several missing pieces to really have it work well.

Let me know what is still missing/doesn't work and I can add it. At the
moment the only known issue I know of is a missing SD card driver in U-
Boot.

1: https://github.com/riscv/meta-riscv/issues/143

Alistair

> 
> 
> [1] https://github.com/sifive/HiFive_U-Boot
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