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

[Jagan Teki]

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?

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.

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