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

[Simon Glass]

Hi,

On 18 January 2016 at 02:39, Sjoerd Simons
<sjoerd.simons at collabora.co.uk> wrote:
> 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?
>
>

It would certainly be great if we can use the boot ROM code. This is
what we do on exynos and it makes a big difference to the SPL size.

Regards,
Simon