[U-Boot] 2015.10-rc2 Chromebook Snow boot failure

[Simon Glass]

Hi Misha,

On 24 August 2015 at 13:50, Misha Komarovskiy <zombah at gmail.com> wrote:
> Hello Simon,
>
> On Mon, Aug 24, 2015 at 7:58 PM, Simon Glass <sjg at chromium.org> wrote:
>>
>> Hi Misha,
>>
>> On 24 August 2015 at 03:55, Misha Komarovskiy <zombah at gmail.com> wrote:
>> > Hello Simon,
>> > Confirmed, with vdd_arm set 1.1, snow boots fine.
>> > ---
>> > Best Regards,
>> > Misha Komarovskiy
>> > zombahatgmaildotcom
>>
>> Please avoid top posting as it leads to a confusing thread.
>>
>
> Will follow this rule in future.
>
>>
>> Would you like to send a patch to update this?
>>
>
> Sure i can, it is easy with advice your gave.
> Better to use if condition CONFIG_TARGET_SNOW or rise
> overall vdd_arm clock?

Rising the overall clock should be fine.
>
>>
>> >
>> >
>> > On Mon, Aug 24, 2015 at 12:31 PM, Misha Komarovskiy <zombah at gmail.com>
>> > wrote:
>> >> Hello Simon,
>> >> 2015.07 and 2015.10-rc1 both boot fine. I use this U-Boot as third
>> >> stage from SD card/USB stick, im not quite
>> >> sure what right name for this position from reset vector.
>> >> I will try to increase  ret = exynos_set_regulator("vdd_arm",
>> >> 1000000); to 1100000 and report result.
>>
>> You say it is a 3rd-stage - does that mean you are booting U-Boot
>> after the existing SPL and U-Boot have already run? That would explain
>> the problem, since the built-in U-Boot sets the CPU speed to maximum.
>>
>
> openSUSE, my linux distro, use chained nv-U-Boot method: factory bootloaders
> stay on their places, USB Boot triggered by enabling dev mode in Chrome OS
> and ctrl-U combo on power on to read second stage Das U-Boot from SD card or
> USB storage, which is upsream version.

Ah yes that explains it.

>
>>
>> We don't have support for CPU clock adjustment in mainline yet.
>>
>> >> ---
>> >> Best Regards,
>> >> Misha Komarovskiy
>> >> zombahatgmaildotcom
>> >>
>> >>
>> >> On Mon, Aug 24, 2015 at 12:21 AM, Simon Glass <sjg at chromium.org> wrote:
>> >>> Hi,
>> >>>
>> >>> On 21 August 2015 at 09:55, Misha Komarovskiy <zombah at gmail.com>
>> >>> wrote:
>> >>>> Hello,
>> >>>> I have failure in attempt to boot Chromebook Snow with 2015.10-rc2
>> >>>> build snow_defconfig, here is error message, it maybe not full as i
>> >>>> have some noise on serial console with device:
>> >>>>
>> >>>> U-Boot 2015.10-rc2 (Aug 21 2015 - 15:43:43 +0000) for snow
>> >>>> GPU:   Exynos5250 @ 1.7 GHz
>> >>>> Model: Google Snow
>> >>>> Board: Google Snow
>> >>>> DRAM:  2 GiB
>> >>>> ERROR: read error from device: bad39118 register: 0x1e!
>> >>>> at drivers/power/pmic/max77686.c:44/max77686_read()
>> >>>> initcall sequence bfdaf3bc failed at call 43e0418c (err=-5)
>> >>>> ### ERROR ### Please RESET the board ###
>> >>>
>> >>> Register 1e is the BUCK3 voltage - see max77686.h.
>> >>>
>> >>> I don't get the same addresses as you but I suppose we are using
>> >>> different toolchains.
>> >>>
>> >>> But this is probably being called from exynos_power_init().
>> >>>
>> >>> The ARM voltage is set to 1.0V. I wonder if that is borderline? We
>> >>> could increase it perhaps to 1.1V. - See the exynos_set_regulator()
>> >>> line for vdd_arm.
>> >>>
>> >>> It was previous 1.3V in 2015.07 - see max77686_init().
>> >>>
>> >>> Are you starting U-Boot SPL directly from the reset vector?
>> >>>
>> >>> Regards,
>> >>> Simon
>>
>> Regards,
>> Simon
>
>
> ---
> Best Regards,
> Misha Komarovskiy
> zombahatgmaildotcom

Regards,
Simon