[U-Boot] [PATCH 43/50] rockchip: pinctrl: Reduce the size for SPL

[Sjoerd Simons]

On Thu, 2016-01-14 at 08:51 -0700, Simon Glass wrote:
> Hi Eddie,
> 
> On 14 January 2016 at 05:47, Eddie Cai <eddie.cai.kernel at gmail.com>
> wrote:
> > Hi Simon
> > 
> > I think the best way to reduce SPL size is to jump back to boot
> > rom.
> > Which don't require eMMC, SD card driver in SPL any more. Even
> > clock
> > and pinctrl driver is not required. All we need is DDR
> > initialization.
> > We should do as little thing as possible in SPL and let U-boot take
> > care others.
> > 
> 
> Is it possible to use the ROM to load U-Boot and then get control
> back
> before jumping to it? If so, then I agree this would be best.
> 
> Ideally we just need a routine we can call which can load from
> eMMC/SD.

Incidentally I've been playing with this a bit over the last week.
Mostly because I wanted to load u-boot over USB OTG to make it simpler
to quickly test things (e.g. to test my networking series more easily).

I've got some work in progress code to jump back to the bootrom after
the SPL which allows me to load u-boot via USB OTG as well, which is
great start. 

Unfortunately it seems that loading a kernel after that will cause the
kernel to wedge during early boot. Initial analysis shows it doesn't
get interrupts from the architecture timer, but it might well be
interrupts don't work at all... 

Eddie, any ideas what the maskrom code might do different with the
interrupt setup if loading things over OTG vs. from MMC? 



> Regards,
> Simon
> 
> > Thanks
> > 
> > Eddie
> [snip]
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-- 
Sjoerd Simons
Collabora Ltd.