[U-Boot] rk3288: 32KB SPL size restriction

[Dr. Philipp Tomsich]

> On 23 Aug 2017, at 20:44, Jagan Teki <jagannadh.teki at gmail.com> wrote:
> 
> On Wed, Aug 23, 2017 at 6:22 PM, Dr. Philipp Tomsich
> <philipp.tomsich at theobroma-systems.com> wrote:
>> 
>>> On 23 Aug 2017, at 13:19, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>> 
>>> Hi Philipp,
>>> 
>>> On Tue, Aug 22, 2017 at 5:41 PM, Dr. Philipp Tomsich
>>> <philipp.tomsich at theobroma-systems.com> wrote:
>>>> 
>>>>> On 22 Aug 2017, at 14:05, Jagan Teki <jagannadh.teki at gmail.com> wrote:
>>>>> 
>>>>> Philipp and Kever - Thanks for the response.
>>>>> 
>>>>> Few comment below.
>>>>> 
>>>>> On Thu, Aug 17, 2017 at 2:02 PM, Dr. Philipp Tomsich
>>>>> <philipp.tomsich at theobroma-systems.com> wrote:
>>>>>> Jagan,
>>>>>> 
>>>>>>> On 17 Aug 2017, at 08:39, Kever Yang <kever.yang at rock-chips.com> wrote:
>>>>>>> 
>>>>>>> Hi Jagan,
>>>>>>> 
>>>>>>> 
>>>>>>> On 08/10/2017 05:07 PM, Jagan Teki wrote:
>>>>>>>> Hi Simon/Philipp or any,
>>>>>>>> 
>>>>>>>> I believe rk3288 has 20KB BootRom and 100KB internal SRAM and current
>>>>>>>> u-boot can archive the maximum size of u-boot-spl-dtb.bin which the
>>>>>>>> boot ROM will read is 32KB, do we have any possibility to increase the
>>>>>>>> SPL size here.
>>>>>>> 
>>>>>>> The limitation is decide by the boot rom design, so we are not able
>>>>>>> to change this. Most of Rockchip SoCs have this limitation except RK3399.
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> - Kever
>>>>>>>> 
>>>>>>>> # ./tools/mkimage -n rk3288 -T rksd -d ./spl/u-boot-spl-dtb.bin out.img
>>>>>>>> Warning: SPL image is too large (size 0x9000) and will not boot
>>>>>>>> Error: image verification failed
>>>>>>>> 
>>>>>>>> I tried to increase the spl_size from spl_infos (on tools/rkcommon.c)
>>>>>>>> but not able to boot.
>>>>>> 
>>>>>> I should have read this more carefully (I only parsed the 20KB and
>>>>>> jumped to the conclusion that your had the error already when crossing
>>>>>> the 20KB limit—even though 0x8000 bytes where allowed in mkimage)…
>>>>> 
>>>>> Sorry I really didn't understand the size constraint here, because SPL
>>>>> can be boot file after ROM handoff. Can't this sit on 100KB of SRAM?
>>>> 
>>>> The ROM usually has different size constraints for each stage.
>>>> 
>>>> E.g. for the RK3368 (just been there, done that), the first stage has a
>>>> 0x7000 byte limit and the next stage (loaded to 0x0 in DRAM) has a
>>>> much larger limit. Note that the SRAM on the 3368 has a capacity of
>>>> 0x10000 bytes, so the size limit is also quite pronounced.
>>> 
>>> OK, by looking at your rk3368[1] patch I think the first stage runs
>>> under 0x7000 is TPL? and next stage(probably SPL) doesn't have limit
>>> since SPL running here in DDR since DDR initialized DDR in TPL itself.
>>> this is what the space distributed here?
>> 
>> Yes, although there is some size limit even for SPL.
>> If you are going for a falcon-mode implementation on the 3288, you will
>> probably want to use TPL for DRAM setup and maybe clocking up the
>> cores (I don’t know the constraints on what clocks the BROM needs
>> untouched) and then have SPL w/ falcon mode loaded by the BROM.
> 
> So, TPL should have DDR and MMC, and fit into 0x8000 bytes and SPL
> will load from MMC and launch u-boot. Do we need spl_bootrom in TPL
> instead of MMC? if so where we need to copy SPL?

You probably just want DRAM-init and clocking and have everything else
in SPL (for the falcon use-case).  The BROM will magically load the SPL
stage for you, so no need for MMC support in TPL.

I don’t know the constraints on the RK3288, so I can’t comment on whether
it’s 0x8000 or some other number…

> My understanding is that TPL should have DDR and MMC and create
> mkimage (that anyway fits within 0x8000) and SPL should have all +
> falcon support and copy the SPL in 128KB. So-that TPL will load SPL
> from MMC same way as how SPL loads U-Boot in current code.

In this configuration, the TPL would be rather small and SPL will do
almost all of the heavy lifting.
	TPL:	DRAM init (and possibly some of the clocking)
	SPL:	clocks, MMC, falcon-loader

> 
> thanks!
> -- 
> Jagan Teki
> Free Software Engineer | www.openedev.com
> U-Boot, Linux | Upstream Maintainer
> Hyderabad, India.