[U-Boot] [PATCH] serial: 16550: Add JZ47xx support

[Marek Vasut]

On 05/26/2016 01:46 PM, Paul Burton wrote:
> On Thu, May 26, 2016 at 12:21:23AM +0200, Marek Vasut wrote:
>> Not for SPL, which has 14 kiB size limit and it is itching to overflow.
>> I am literally counting bytes in the SPL and removing slop from
>> structures to make it fit, just barely. With the USB loader, I can
>> brutalize the SPL into having extremely rudimentary UART support now
>> (like printch() being the most advanced output mechanism, but you can
>> only use it three times, otherwise the code won't fit and the board is
>> eaten by demons) and this is where this patch comes into play.
>>
>> So yes, for full u-boot, this _should_ be part of DT. For SPL, please apply.
> 
> Hi Marek,

Hi!

> Interesting :) May I ask which platform/SoC you're working with? Have
> you seen the (unfortunately currently out of tree) port we did for the
> JZ4780-based Ci20? I recall the pain of squeezing SPL down to a small
> enough size well...

I bought the CI20, yeah. I started with that tree and am now getting it
into mainline shape. I actually managed to optimize the SPL, so it does
not overflow. One of the things which helped a lot was removing slop[1]
from the structures and using appropriate data types in them (like don't
use u32 to store an 8bit number). I also tinified the MMC stack, so that
it won't pull in too much useless code.

At this point, I have a u-boot running from SD card and the SD driver in
full U-Boot is already probing from DT and using DM. I sent Daniel the
updated patches, but they are still work in progress. Nonetheless, if
you want me forward that to you as well, let me know.

I plan to get this CI20 submitted at some point this or next week, so it
can land in 2016.07 (I hope!) and then debian and fedora-mips (and other
distros) can pick it up and package proper. That's how I see it.

btw. what is the linux support status of the ci20 ? Is anyone working
on that? I saw the DTS in Linux, but it's pretty bare-bones.

btw2. can I get the ci40 anywhere or is that just unobtainium board ?

> https://github.com/MIPS/CI20_u-boot
> 
> Thanks,
>     Paul
> 

[1] http://www.catb.org/esr/structure-packing/

-- 
Best regards,
Marek Vasut