linux-kernel - Re: [PATCH] remoteproc: Add module parameter 'auto

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Message-ID: <20201120223701.GF4137289@xps15>
Date:   Fri, 20 Nov 2020 15:37:01 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>, od@...c.me,
        linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] remoteproc: Add module parameter 'auto_boot'

Hi Paul,

On Sun, Nov 15, 2020 at 11:50:56AM +0000, Paul Cercueil wrote:
> Until now the remoteproc core would always default to trying to boot the
> remote processor at startup. The various remoteproc drivers could
> however override that setting.
> 
> Whether or not we want the remote processor to boot, really depends on
> the nature of the processor itself - a processor built into a WiFi chip
> will need to be booted for the WiFi hardware to be usable, for instance,
> but a general-purpose co-processor does not have any predeterminated
> function, and as such we cannot assume that the OS will want the
> processor to be booted - yet alone that we have a single do-it-all
> firmware to load.
>

If I understand correctly you have various remote processors that use the same firmware
but are serving different purposes - is this correct?
 
> Add a 'auto_boot' module parameter that instructs the remoteproc whether
> or not it should auto-boot the remote processor, which will default to
> "true" to respect the previous behaviour.
>

Given that the core can't be a module I wonder if this isn't something that
would be better off in the specific platform driver or the device tree...  Other
people might have an opinion as well.

Thanks,
Mathieu

> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>  drivers/remoteproc/remoteproc_core.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index dab2c0f5caf0..687b1bfd49db 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -44,6 +44,11 @@
>  
>  #define HIGH_BITS_MASK 0xFFFFFFFF00000000ULL
>  
> +static bool auto_boot = true;
> +module_param(auto_boot, bool, 0400);
> +MODULE_PARM_DESC(auto_boot,
> +		 "Auto-boot the remote processor [default=true]");
> +
>  static DEFINE_MUTEX(rproc_list_mutex);
>  static LIST_HEAD(rproc_list);
>  static struct notifier_block rproc_panic_nb;
> @@ -2176,7 +2181,7 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
>  		return NULL;
>  
>  	rproc->priv = &rproc[1];
> -	rproc->auto_boot = true;
> +	rproc->auto_boot = auto_boot;
>  	rproc->elf_class = ELFCLASSNONE;
>  	rproc->elf_machine = EM_NONE;
>  
> -- 
> 2.29.2
>