From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>, Ahmad Fatoum <ahmad@a3f.at>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 1/3] ARM: i.MX: boot: correctly handle SRC_SBMR1 override via SRC_GPR9
Date: Fri, 8 May 2020 08:41:41 +0200 [thread overview]
Message-ID: <b7a02590-a63b-9681-c5f5-8475dd85886d@pengutronix.de> (raw)
In-Reply-To: <ccef9a1d-0887-7573-966d-fee2eba57907@pengutronix.de>
Hello,
On 4/27/20 10:28 AM, Ahmad Fatoum wrote:
> Hello,
>
> On 4/27/20 10:07 AM, Sascha Hauer wrote:
>> On Mon, Apr 27, 2020 at 09:13:49AM +0200, Ahmad Fatoum wrote:
>>> `mw 0x20d8040 0x08000030; mw 0x20d8044 0x10000000; reset` issued on an
>>> i.MX6Q forces boot from the ecspi1. This is because the BootROM reads
>>> the boot mode out of SRC_GPR9 instead of SRC_SBMR1 whenever SRC_GPR10
>>> has its 28th bit set.
>>
>> Is this documented somewhere? The reference Manual marks SRC_GPR9 and
>> SRC_GPR10 as
>>
>> | This register is used by the ROM code and should not be used
>> | by application software.
Seems it's indeed documented in the IMX6ULRM (Rev.2 03/27).
See Table 8-6. Persistent bits.
Can the patches be applied or do you need me to change something?
>
> Not documented anywhere, except for U-Boot's bmode command and boot
> source determination code:
>
> https://github.com/trini/u-boot/blob/v2020.04/arch/arm/mach-imx/mx6/soc.c#L560
> https://github.com/trini/u-boot/blob/v2020.04/arch/arm/mach-imx/init.c#L104
>
>> And why do you depend on this behaviour?
>
> It's a useful debugging aid, when strap pins aren't easily accessible,
> because then your only other option is then to fuse to affect the boot
> (or short your SPI I/O pins).
>
> I am preparing code to provide a generic reboot mode functionality
> in barebox. This would among others cover the functionality of
> the U-Boot bmode command and these patches here are prerequisites,
> so the boot source detection remains accurate.
>
> Cheers
>
>
>>
>> Sascha
>>
>
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next prev parent reply other threads:[~2020-05-08 6:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 7:13 Ahmad Fatoum
2020-04-27 7:13 ` [PATCH 2/3] ARM: i.MX: boot: interpret reserved boot as forced serial Ahmad Fatoum
2020-04-27 7:13 ` [PATCH 3/3] ARM: i.MX6: boot: handle i.MX6UL differences Ahmad Fatoum
2020-04-27 8:07 ` [PATCH 1/3] ARM: i.MX: boot: correctly handle SRC_SBMR1 override via SRC_GPR9 Sascha Hauer
2020-04-27 8:28 ` Ahmad Fatoum
2020-05-08 6:41 ` Ahmad Fatoum [this message]
2020-05-08 12:07 ` Sascha Hauer
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