[PATCH 2/6] lib: sbi_hsm: handle failure when hart_stop returns SBI_ENOTSUPP

[Anup Patel]

On Wed, Jan 4, 2023 at 12:00 PM Yu Chien Peter Lin
<peterlin at andestech.com> wrote:
>
> Make use of generic warm-boot path when platform hart_stop callback
> returns SBI_ENOTSUPP, in case certain hart can not turn off its
> power domain, or it detects some error occured in power management
> unit, it can fall through warmboot flow and wait for interrupt in
> sbi_hsm_hart_wait().
>
> Also improves comment in sbi_hsm_hart_wait().
>
> Signed-off-by: Yu Chien Peter Lin <peterlin at andestech.com>

Looks good to me.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup

> ---
> On ae350-ax25mp, hart0 shares power domain with L2-cache, thus turning
> it off would break working system.
> ---
>  include/sbi/sbi_hsm.h | 8 ++++++--
>  lib/sbi/sbi_hsm.c     | 7 +++----
>  2 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/include/sbi/sbi_hsm.h b/include/sbi/sbi_hsm.h
> index d6cc468..1e23884 100644
> --- a/include/sbi/sbi_hsm.h
> +++ b/include/sbi/sbi_hsm.h
> @@ -21,8 +21,12 @@ struct sbi_hsm_device {
>         int (*hart_start)(u32 hartid, ulong saddr);
>
>         /**
> -        * Stop (or power-down) the current hart from running. This call
> -        * doesn't expect to return if success.
> +        * Stop (or power-down) the current hart from running.
> +        *
> +        * Return SBI_ENOTSUPP if the hart does not support platform-specific
> +        * stop actions.
> +        *
> +        * For successful stop, the call won't return.
>          */
>         int (*hart_stop)(void);
>
> diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
> index 836008f..b89253b 100644
> --- a/lib/sbi/sbi_hsm.c
> +++ b/lib/sbi/sbi_hsm.c
> @@ -116,7 +116,7 @@ static void sbi_hsm_hart_wait(struct sbi_scratch *scratch, u32 hartid)
>         /* Set MSIE and MEIE bits to receive IPI */
>         csr_set(CSR_MIE, MIP_MSIP | MIP_MEIP);
>
> -       /* Wait for hart_add call*/
> +       /* Wait for state transition requested by sbi_hsm_hart_start() */
>         while (atomic_read(&hdata->state) != SBI_HSM_STATE_START_PENDING) {
>                 wfi();
>         };
> @@ -228,9 +228,8 @@ void __noreturn sbi_hsm_exit(struct sbi_scratch *scratch)
>                 goto fail_exit;
>
>         if (hsm_device_has_hart_hotplug()) {
> -               hsm_device_hart_stop();
> -               /* It should never reach here */
> -               goto fail_exit;
> +               if (hsm_device_hart_stop() != SBI_ENOTSUPP)
> +                       goto fail_exit;
>         }
>
>         /**
> --
> 2.34.1
>
>
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