Re: [PATCH] remoteproc: Add module parameter 'auto_boot'

[Paul Cercueil]

Hi Mathieu,

Le ven. 20 nov. 2020 à 15:37, Mathieu Poirier 
<mathieu.poirier@xxxxxxxxxx> a écrit :
> 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?

That's the opposite actually. I have one remote processor which is 
general-purpose, and as such userspace may or may not want it started 
at boot time - depending on what it wants to do with it. The kernel 
shouldn't decide itself whether or not the remote processor should be 
started, because that's policy.

> >  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.

Hardcoded in the platform driver or flagged in the device tree, doesn't 
change the fundamental problem - it should be up to the userspace to 
decide whether or not the remote processor should boot.

Cheers,
-Paul

> >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  ---
> >   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