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

[Paul Cercueil]

Hi Suman,

Le ven. 20 nov. 2020 à 17:06, Suman Anna <s-anna@xxxxxx> a écrit :
> Hi Paul,
>
> On 11/20/20 4:37 PM, Mathieu Poirier wrote:
> >  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.
>
> I agree. Even it is a module, all it is setting up is default 
> behavior, and
> doesn't buy you much. If you have one or more remoteproc drivers 
> supporting
> different instances, and each one wants different behavior, you would 
> have to
> customize it in the drivers anyway. ST drivers are customizing this 
> using a DT flag.

Devicetree is supposed to describe the hardware, not how you're 
supposed to use the hardware...

> Given that the individual platform drivers have to be modules, is 
> there any
> issue in customizing this in your platform driver?

No, I can patch the platform driver instead, but to me it clearly is a 
core issue.

Cheers,
-Paul

> regards
> Suman
>
> >  Thanks,
> >  Mathieu
> >
> > >  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