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SubjectRe: [RFC] ARM: exynos: Fix imprecise abort during Exynos5422 suspend to RAM
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Hi Krzysztof,

On 2018-07-18 21:59, Krzysztof Kozlowski wrote:
> Suspend to RAM on Odroid XU3/XU4/HC1 family (Exynos5422) causes
> imprecise abort:
>
> PM: Syncing filesystems ... done.
> Freezing user space processes ... (elapsed 0.003 seconds) done.
> OOM killer disabled.
> Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done.
> wake enabled for irq 139
> Disabling non-boot CPUs ...
> IRQ51 no longer affine to CPU1
> IRQ52 no longer affine to CPU2
> IRQ53 no longer affine to CPU3
> IRQ54 no longer affine to CPU4
> IRQ55 no longer affine to CPU5
> IRQ56 no longer affine to CPU6
> cpu cpu4: Dropping the link to regulator.40
> IRQ57 no longer affine to CPU7
> Unhandled fault: external abort on non-linefetch (0x1008) at 0xf081a028
> Internal error: : 1008 [#1] PREEMPT SMP ARM
>
> with last call trace in exynos_suspend_enter().
>
> The abort is caused by writing to register in secure part of sysram.
> All Exynos5422 devices, including Hardkernel Odroid boards, boot with
> TrustZone in non-secure mode therefore they should access non-secure
> sysram.
>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
>
> ---
>
> Comments, whether my understanding is correct, are welcomed!

The decision, weather to use secure or non-secure sysram depends on the
enabled TrustZone interface IMHO. Exynos5420 PeachPIT and Exynos5800 PeachPI
don't use TrustZone and don't have 'firmware' node in dts, thus they should
keep existing code.

> ---
> Documentation/arm/Samsung/Bootloader-interface.txt | 1 +
> arch/arm/mach-exynos/suspend.c | 6 +++---
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/arm/Samsung/Bootloader-interface.txt b/Documentation/arm/Samsung/Bootloader-interface.txt
> index ed494ac0beb2..d17ed518a7ea 100644
> --- a/Documentation/arm/Samsung/Bootloader-interface.txt
> +++ b/Documentation/arm/Samsung/Bootloader-interface.txt
> @@ -26,6 +26,7 @@ Offset Value Purpose
> 0x20 0xfcba0d10 (Magic cookie) AFTR
> 0x24 exynos_cpu_resume_ns AFTR
> 0x28 + 4*cpu 0x8 (Magic cookie, Exynos3250) AFTR
> +0x28 0x0 or last value during resume (Exynos542x) System suspend
>
>
> 2. Secure mode
> diff --git a/arch/arm/mach-exynos/suspend.c b/arch/arm/mach-exynos/suspend.c
> index d3db306a5a70..0ec52f442b97 100644
> --- a/arch/arm/mach-exynos/suspend.c
> +++ b/arch/arm/mach-exynos/suspend.c
> @@ -256,7 +256,7 @@ static int exynos5420_cpu_suspend(unsigned long arg)
> unsigned int cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
> unsigned int cpu = MPIDR_AFFINITY_LEVEL(mpidr, 0);
>
> - writel_relaxed(0x0, sysram_base_addr + EXYNOS5420_CPU_STATE);
> + writel_relaxed(0x0, sysram_ns_base_addr + EXYNOS5420_CPU_STATE);
>
> if (IS_ENABLED(CONFIG_EXYNOS5420_MCPM)) {
> mcpm_set_entry_vector(cpu, cluster, exynos_cpu_resume);
> @@ -328,7 +328,7 @@ static void exynos5420_pm_prepare(void)
> * needs to restore it back in case, the primary cpu fails to
> * suspend for any reason.
> */
> - exynos5420_cpu_state = readl_relaxed(sysram_base_addr +
> + exynos5420_cpu_state = readl_relaxed(sysram_ns_base_addr +
> EXYNOS5420_CPU_STATE);
>
> exynos_pm_enter_sleep_mode();
> @@ -448,7 +448,7 @@ static void exynos5420_pm_resume(void)
>
> /* Restore the sysram cpu state register */
> writel_relaxed(exynos5420_cpu_state,
> - sysram_base_addr + EXYNOS5420_CPU_STATE);
> + sysram_ns_base_addr + EXYNOS5420_CPU_STATE);
>
> pmu_raw_writel(EXYNOS5420_USE_STANDBY_WFI_ALL,
> S5P_CENTRAL_SEQ_OPTION);

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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