[U-Boot] [PATCH 12/13] armv7: support rk3066 early back to bootrom in start.S

[Paweł Jarosz]

Hi Simon


W dniu 14.06.2017 o 13:06, Simon Glass pisze:
> +Philippe
>
> Hi Pawel,
>
> On 12 June 2017 at 17:50, Simon Glass <sjg at chromium.org> wrote:
>> Hi Pawel,
>>
>> On 9 June 2017 at 06:31, Paweł Jarosz <paweljarosz3691 at gmail.com> wrote:
>>>
>>> W dniu 09.06.2017 o 13:46, Heiko Stuebner pisze:
>>>
>>>> Am Mittwoch, 7. Juni 2017, 17:37:13 CEST schrieb Paweł Jarosz:
>>>>> Hi Simon,
>>>>>
>>>>>
>>>>> W dniu 06.06.2017 o 23:10, Simon Glass pisze:
>>>>>> Hi Pawel,
>>>>>>
>>>>>> On 6 June 2017 at 12:53, Paweł Jarosz <paweljarosz3691 at gmail.com> wrote:
>>>>>>> Rockchip bootrom first reads 1KB data from nand at offset 0x10080C00
>>>>>>> and
>>>>>>> executes it. Then waits for back to bootrom and loads another 32KB to
>>>>>>> sram
>>>>>>> which also executes. Sdram initialisation code needs to be in one of
>>>>>>> these two
>>>>>>> steps. Then bootloader loads another ~200KB of data at offset
>>>>>>> 0x60000000
>>>>>>> and jumps to it.
>>>>>>>
>>>>>>> 32KB of data is a little low for tpl + spl part and ~200KB data is to
>>>>>>> low for
>>>>>>> u-boot part(for example to boot from mmc you need to disable usb
>>>>>>> support.
>>>>>>>
>>>>>>> My solution to size problem is to move sdram initialisation code to tpl
>>>>>>> stage,
>>>>>>> move spl part to third stage(reading 200KB data) and add support for
>>>>>>> loading
>>>>>>> u-boot by spl from ext2/4, fat partitions.
>>>>>>>
>>>>>>> But moving sdram initialisation code to tpl increases size of tpl above
>>>>>>> 1KB
>>>>>>> (first boot stage). Solution to this is to add code which will be below
>>>>>>> 1KB
>>>>>>> offset in tpl binary and do back to bootrom at very beginning of the
>>>>>>> tpl
>>>>>>> execution.
>>>>>> So do you mean that TPL starts and then loads more of itself? Why not
>>>>>> put SDRAM init in SPL? You say above that 32KB is 'too low', but It's
>>>>>> not clear why.
>>>>> Ad.1 No. Tpl starts and at the first execution returns to bootrom.
>>>>> Bootrom then loads
>>>>> rest of the tpl (31KB) and executes it for a second time.
>>>>>
>>>>> Ad.2,3 Due to size issues (200KB limit) i needed to move main u-boot to
>>>>> mmc. To load u-boot from
>>>>> mmc by SPL (there is 32KB bootrom limit, not enough space for mmc
>>>>> support) i moved SPL to sdram.
>>>>> Code executed in sdram can't mess with sdram settings because it will
>>>>> hang the board. Sdram setup
>>>>> needs to be done by code in SRAM (tpl).
>>>> At least the rk3288-Firefly was able to also have mmc stack in the SPL in
>>>> the past, without requiring the back_to_bootrom at all. So question would
>>>> be why this doesn't fit anymore, or on the rk3066 specifically.
>>>>
>>>> Also, it seems like I got my hands on a preliminary (linux/mtd) nand
>>>> driver
>>>> (rk3228 but cursory glance at the registers suggests that it may actually
>>>> work on previous socs down to the rk3066 as well) and it may be possible
>>>> to adapt that for uboot, therefore making the spl able to also load the
>>>> full u-boot from without needing back_to_bootrom.
>>>>
>>>>
>>>> Heiko
>>> I was not able to get mmc support on rk3066 in spl in ~31kb (32kb - 1kb for
>>> tpl)size limit.
>>> One (or two i didn't check how much) back to bootrom is required on rk3066.
>>> If not done bootrom stays in weird state and halts on bringup secondary cpu
>>> in kernel. So it's rk3066 specific.
>> What size do you get? With firefly-rk3288 I get about 25KB with SDRAM
>> init and MMC stack. Are you building with Thumb 2?
>>
>> If you are on irc we could try to clear this up more quicky (I am sjg1)
> To summarise where I think we got to:
>
> - move DRAM init into SPL
> - either have a very small TPL which just returns to boot ROM, or
> adjust start.S to return to the boot room early in SPL to load the
> other 31KB
>
> Can you please post to the mailing list with your thoughts on this so
> that others (including rockchip) can chime in? I think either will
> work but I think others will have an opinion.
>
> Regards,
> Simon

About moving dram init to spl i agree.

I think early back to bootrom in start.S is a good solution as it would 
give me 1KB more space for spl and i could drop hacks like jumping to 
spl in tpl board file. But I would like to hear the opinion of other 
people on this.

Also i got a nandc driver from Heiko and i would like to adopt it for 
u-boot in the next version. Is it ok?

Paweł