linux-kernel - Re: [PATCH 2/2] LoongArch: Fix ACPI standard register based S3 support

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Message-ID: <CAAhV-H7VKGMAH10S4sOZLkbgkUSMAYzpYt-dL83S0Vg286PsaQ@mail.gmail.com>
Date: Fri, 14 Jun 2024 10:11:28 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Jiaxun Yang <jiaxun.yang@...goat.com>, Jianmin Lv <lvjianmin@...ngson.cn>
Cc: WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 2/2] LoongArch: Fix ACPI standard register based S3 support

Hi, Jiaxun,

On Fri, Jun 14, 2024 at 12:41 AM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>
> Most LoongArch 64 machines are using custom "SADR" ACPI extension
> to perform ACPI S3 sleep. However the standard ACPI way to perform
> sleep is to write a value to ACPI PM1/SLEEP_CTL register, and this
> is never supported properly in kernel.
Maybe our hardware is insane so we need "SADR", if so, this patch may
break real hardware. What's your opinion, Jianmin?

Huacai

>
> Fix standard S3 sleep by providing a fallback DoSuspend function
> which calls ACPI's acpi_enter_sleep_state routine when SADR is
> not provided by the firmware.
>
> Also fix suspend assembly code so that ra is set properly before
> go into sleep routine. (Previously linked address of jirl was set
> to a0, some firmware do require return address in a0 but it's
> already set with la.pcrel before).
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> ---
>  arch/loongarch/power/platform.c    | 24 ++++++++++++++++++------
>  arch/loongarch/power/suspend_asm.S |  2 +-
>  2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/arch/loongarch/power/platform.c b/arch/loongarch/power/platform.c
> index 3ea8e07aa225..2aea41f8e3ff 100644
> --- a/arch/loongarch/power/platform.c
> +++ b/arch/loongarch/power/platform.c
> @@ -34,22 +34,34 @@ void enable_pci_wakeup(void)
>                 acpi_write_bit_register(ACPI_BITREG_PCIEXP_WAKE_DISABLE, 0);
>  }
>
> +static void acpi_suspend_register_fallback(void)
> +{
> +       acpi_enter_sleep_state(ACPI_STATE_S3);
> +}
> +
>  static int __init loongson3_acpi_suspend_init(void)
>  {
>  #ifdef CONFIG_ACPI
>         acpi_status status;
>         uint64_t suspend_addr = 0;
>
> -       if (acpi_disabled || acpi_gbl_reduced_hardware)
> +       if (acpi_disabled)
>                 return 0;
>
> -       acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
> +       if (!acpi_sleep_state_supported(ACPI_STATE_S3))
> +               return 0;
> +
> +       if (!acpi_gbl_reduced_hardware)
> +               acpi_write_bit_register(ACPI_BITREG_SCI_ENABLE, 1);
> +
>         status = acpi_evaluate_integer(NULL, "\\SADR", NULL, &suspend_addr);
> -       if (ACPI_FAILURE(status) || !suspend_addr) {
> -               pr_err("ACPI S3 is not support!\n");
> -               return -1;
> +       if (!ACPI_FAILURE(status) && suspend_addr) {
> +               loongson_sysconf.suspend_addr = (u64)phys_to_virt(PHYSADDR(suspend_addr));
> +               return 0;
>         }
> -       loongson_sysconf.suspend_addr = (u64)phys_to_virt(PHYSADDR(suspend_addr));
> +
> +       pr_info("ACPI S3 supported with hw register fallback\n");
> +       loongson_sysconf.suspend_addr = (u64)acpi_suspend_register_fallback;
>  #endif
>         return 0;
>  }
> diff --git a/arch/loongarch/power/suspend_asm.S b/arch/loongarch/power/suspend_asm.S
> index 6fdd74eb219b..fe08dbb73c87 100644
> --- a/arch/loongarch/power/suspend_asm.S
> +++ b/arch/loongarch/power/suspend_asm.S
> @@ -66,7 +66,7 @@ SYM_FUNC_START(loongarch_suspend_enter)
>         la.pcrel        a0, loongarch_wakeup_start
>         la.pcrel        t0, loongarch_suspend_addr
>         ld.d            t0, t0, 0
> -       jirl            a0, t0, 0 /* Call BIOS's STR sleep routine */
> +       jirl            ra, t0, 0 /* Call BIOS's STR sleep routine */
>
>         /*
>          * This is where we return upon wakeup.
>
> --
> 2.43.0
>
>