[U-Boot] [PATCH] arm: exynos: Use the generic lowlevel_init instead of the specific one
Alison Wang
alison.wang at nxp.com
Tue Nov 15 09:04:14 CET 2016
Hi, Thomas,
> On Tue, Nov 15, 2016 at 1:03 PM, Alison Wang <alison.wang at nxp.com>
> wrote:
> > Hi, Thomas, Alex and York,
> >
> > Before there are some discussions about this patch, could we make a
> solution now? Or else, the patches about [PATCH v8 0/3] armv8: Support
> loading 32-bit OS in AArch32 execution state can't be merged, as the
> compiling will fail without this patch.
> >
> > Thomas, is ARMV8_MULTIENTRY enabled on Exynos7420 now? If not, is
> there a good way to enable ARMV8_MULTIENTRY on Exynos7420 now?
>
> It is not yet enabled. I will post the ARMV8_MULTIENTRY enable patch
> for Exynos7420 later today. Alternatively, you could include the patch
> listed in the previous email in your series.
>
[Alison Wang] Thanks for your reply. I think it's better to send the patch
by you (the maintainer). Please send it later today. :)
Best Regards,
Alison Wang
>
> >
> > Thanks.
> >
> > Best Regards,
> > Alison Wang
> >
> >> -----Original Message-----
> >> From: Thomas Abraham [mailto:ta.omasab at gmail.com]
> >> Sent: Tuesday, September 20, 2016 4:45 PM
> >> To: Alexander Graf <agraf at suse.de>
> >> Cc: Alison Wang <b18965 at freescale.com>; thomas.ab at samsung.com;
> Minkyu
> >> Kang <mk7.kang at samsung.com>; york sun <york.sun at nxp.com>; U-Boot
> >> Mailing List <u-boot at lists.denx.de>; Jason Jin <jason.jin at nxp.com>
> >> Subject: Re: [U-Boot] [PATCH] arm: exynos: Use the generic
> >> lowlevel_init instead of the specific one
> >>
> >> On Tue, Sep 20, 2016 at 12:03 PM, Alexander Graf <agraf at suse.de>
> wrote:
> >> >
> >> >
> >> > 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.
> >>
> >> Okay.
> >>
> >> >
> >> > How quickly do you think you could make Exynos7 work with
> MULTIENTRY?
> >> >
> >>
> >> Exynos7420 uses CPU 0 of Cluster 1 as boot CPU (master CPU). The
> macro
> >> 'branch_if_master' requires all affinity values to be zero for a CPU
> >> to be identified as a master CPU. And so the boot CPU is incorrectly
> >> detected as a slave CPU. I have tested with the following temporary
> >> workaround to enable ARMV8_MULTIENTRY on Exynos7420. If it looks
> fine,
> >> this can be merged along with Alison's patch.
> >>
> >> Thomas.
> >>
> >> diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-
> >> exynos/Kconfig
> >> index ce2a16f..45c5eeb 100644
> >> --- a/arch/arm/mach-exynos/Kconfig
> >> +++ b/arch/arm/mach-exynos/Kconfig
> >> @@ -126,6 +126,8 @@ choice
> >> config TARGET_ESPRESSO7420
> >> bool "ESPRESSO7420 board"
> >> select ARM64
> >> + select ARMV8_MULTIENTRY
> >> + select ARMV8_SWITCH_TO_EL1
> >> select SUPPORT_SPL
> >> select OF_CONTROL
> >> select SPL_DISABLE_OF_CONTROL
> >> diff --git a/arch/arm/mach-exynos/soc.c b/arch/arm/mach-exynos/soc.c
> >> index f9c7468..6c3ebb0 100644
> >> --- a/arch/arm/mach-exynos/soc.c
> >> +++ b/arch/arm/mach-exynos/soc.c
> >> @@ -9,6 +9,16 @@
> >> #include <asm/io.h>
> >> #include <asm/system.h>
> >>
> >> +#ifdef CONFIG_TARGET_ESPRESSO7420
> >> +/*
> >> + * Exynos7420 uses CPU0 of Cluster-1 as boot CPU. Due to this
> >> branch_if_master
> >> + * fails to identify as the master CPU. As temporary workaround,
> setup
> >> the
> >> + * slave CPU boot address as "_main".
> >> + */
> >> +extern void _main(void);
> >> +void *secondary_boot_addr = (void *)_main;
> >> +#endif /* CONFIG_TARGET_ESPRESSO7420 */
> >> +
> >> void reset_cpu(ulong addr)
> >> {
> >> #ifdef CONFIG_CPU_V7
> >> diff --git a/include/configs/exynos7420-common.h
> >> b/include/configs/exynos7420-common.h
> >> index 9e03962..6f58aef 100644
> >> --- a/include/configs/exynos7420-common.h
> >> +++ b/include/configs/exynos7420-common.h
> >> @@ -48,6 +48,7 @@
> >> #define CONFIG_IRAM_BASE 0x02100000
> >> #define CONFIG_IRAM_SIZE 0x58000
> >> #define CONFIG_IRAM_END (CONFIG_IRAM_BASE +
> >> CONFIG_IRAM_SIZE)
> >> +#define CPU_RELEASE_ADDR secondary_boot_addr
> >>
> >> /* Number of CPUs available */
> >> #define CONFIG_CORE_COUNT 0x8
> >>
> >> >
> >> > Alex
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