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

[Troy Benjegerdes <troy.benjegerdes@sifive.com>]

> 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.

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.


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