Re: [PATCH v5 1/4] firmware: arm_sdei: add sdei_is_present()

[Usama Arif <usama.arif@linux.dev>]

On Mon, 29 Jun 2026 16:07:15 +0100 Kiryl Shutsemau <kirill@shutemov.name> wrote:

> From: "Kiryl Shutsemau (Meta)" <kas@kernel.org>
> 
> invoke_sdei_fn() returns -EIO when no SDEI conduit was probed, and the
> core warns ("Failed to create event ...") on any registration that hits
> that. An optional consumer that registers an event from an unconditional
> initcall would therefore make every boot on a non-SDEI system emit that
> warning for what is simply absent firmware.
> 
> Expose whether SDEI firmware is present so such a consumer can skip
> registration -- and the warning -- when there is nothing to talk to.
> 
> Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
> ---

Can this be merged in patch 3 where this function is actually used?

>  drivers/firmware/arm_sdei.c | 10 ++++++++++
>  include/linux/arm_sdei.h    |  3 +++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
> index f39ed7ba3a38..c161cf263547 100644
> --- a/drivers/firmware/arm_sdei.c
> +++ b/drivers/firmware/arm_sdei.c
> @@ -339,6 +339,16 @@ static void _ipi_unmask_cpu(void *ignored)
>  	sdei_unmask_local_cpu();
>  }
>  
> +/*
> + * Was SDEI firmware probed and is it usable?  Lets optional consumers skip
> + * registering an event -- and the warning a failed registration emits -- on
> + * systems with no SDEI.
> + */
> +bool sdei_is_present(void)
> +{
> +	return sdei_firmware_call;

sdei_firmware_call is a function pointer. The above is correct, but
can we make it sdei_firmware_call != NULL? I think that looks a lot better.

> +}
> +
>  static void _ipi_private_reset(void *ignored)
>  {
>  	int err;
> diff --git a/include/linux/arm_sdei.h b/include/linux/arm_sdei.h
> index f652a5028b59..b07113eeeff7 100644
> --- a/include/linux/arm_sdei.h
> +++ b/include/linux/arm_sdei.h
> @@ -37,6 +37,9 @@ int sdei_event_unregister(u32 event_num);
>  int sdei_event_enable(u32 event_num);
>  int sdei_event_disable(u32 event_num);
>  
> +/* Was SDEI firmware probed and usable? */
> +bool sdei_is_present(void);
> +
>  /* GHES register/unregister helpers */
>  int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,
>  		       sdei_event_callback *critical_cb);
> -- 
> 2.54.0
> 
>