[U-Boot] [PATCH] arm: exynos: Use the generic lowlevel_init instead of the specific one

[Alexander Graf]

On 20.09.16 08:25, Thomas Abraham wrote:
> On Tue, Sep 20, 2016 at 11:35 AM, Alexander Graf <agraf at suse.de> wrote:
>>
>>
>> Am 20.09.2016 um 07:51 schrieb Thomas Abraham <ta.omasab at gmail.com>:
>>
>> Hi Alison,
>>
>>
>> On Mon, Sep 19, 2016 at 7:38 PM, Alexander Graf <agraf at suse.de> wrote:
>>
>>
>>
>> On 09.09.16 10:48, Alison Wang wrote:
>>
>> This patch is to use the the generic lowlevel_init instead of the
>>
>> specific one.
>>
>>
>> Signed-off-by: Alison Wang <alison.wang at nxp.com>
>>
>>
>> If I had to guess, I'd think they only had their own version because the
>>
>> old one required a GIC.
>>
>>
>> I apologize for the delay.
>>
>> The reason for using a custom version was to avoid enabling
>> ARMV8_MULTIENTRY config option since the Exynos7 code was ready for
>> it.
>>
>>
>> Either way, since Samsung doesn't reply, I'm fine potentially breaking
>>
>> their boards if that means that we can make progress for actively
>>
>> maintained ones:
>>
>>
>>  Reviewed-by: Alexander Graf <agraf at suse.de>
>>
>>
>> This patch without the ARMV8_MULTIENTRY and ARMV8_SWITCH_TO_EL1 config
>> options does not switch the boot CPU from EL3 to EL1. So it would be
>> preferable to not merge this patch until ARMV8_MULTIENTRY  is enabled
>> for Exynos7.
>>
>>
>> Why do you want to switch it to EL1 in the first place? Linux is very happy
>> to live in EL2 - which is what we call it in by default.
> 
> Okay, there is no particular requirement to be in EL1 for Exynos7. EL2
> would also be fine. But Exynos7 support in u-boot is not yet ready for
> enabling ARMV8_MULTIENTRY config option. Is there anything be blocked
> due to Exynos7 using a custom lowlevel_init function?

Yes, we're changing the semantics of armv8_switch_to_el2 and
armv8_switch_to_el1:

  http://lists.denx.de/pipermail/u-boot/2016-September/266217.html

which is a prerequisite for AArch32 kernel boot on AArch64 systems.

How quickly do you think you could make Exynos7 work with MULTIENTRY?


Alex