[PATCH] ipmi:si: Add async init to ipmi_si

[PATCH] ipmi:si: Add async init to ipmi_si

[Michal Clapinski]

Added a new config option to allow offloading slow part of
init_ipmi_si. Saves 100ms on my system.

Signed-off-by: Michal Clapinski <mclapinski@google.com>
---
 drivers/char/ipmi/Kconfig        |  8 ++++++
 drivers/char/ipmi/ipmi_si_intf.c | 48 +++++++++++++++++++++-----------
 2 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 669f76000197..8419409dc3b9 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -67,6 +67,14 @@ config IPMI_SI
 	  Currently, only KCS and SMIC are supported.  If
 	  you are using IPMI, you should probably say "y" here.
 
+config IPMI_SI_ASYNC_INIT
+	bool 'Asynchronous initialization of IPMI System Interface'
+	depends on IPMI_SI
+	default n
+	help
+	  Enables asynchronous init of the IPMI System Interface.
+	  It speeds up the boot time.
+
 config IPMI_SSIF
 	tristate 'IPMI SMBus handler (SSIF)'
 	depends on I2C
diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 9a9d12be9bf7..3e422c7df60a 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -39,6 +39,7 @@
 #include <linux/rcupdate.h>
 #include <linux/ipmi.h>
 #include <linux/ipmi_smi.h>
+#include <linux/async.h>
 #include "ipmi_si.h"
 #include "ipmi_si_sm.h"
 #include <linux/string.h>
@@ -2174,25 +2175,10 @@ static bool __init ipmi_smi_info_same(struct smi_info *e1, struct smi_info *e2)
 		e1->io.addr_data == e2->io.addr_data);
 }
 
-static int __init init_ipmi_si(void)
+static int __init smi_init_scan(void)
 {
 	struct smi_info *e, *e2;
 
-	if (initialized)
-		return 0;
-
-	ipmi_hardcode_init();
-
-	pr_info("IPMI System Interface driver\n");
-
-	ipmi_si_platform_init();
-
-	ipmi_si_pci_init();
-
-	ipmi_si_ls2k_init();
-
-	ipmi_si_parisc_init();
-
 	mutex_lock(&smi_infos_lock);
 
 	/*
@@ -2271,6 +2257,36 @@ static int __init init_ipmi_si(void)
 		return 0;
 	}
 }
+
+static void __init async_smi_init(void *data, async_cookie_t cookie)
+{
+	smi_init_scan();
+}
+
+static int __init init_ipmi_si(void)
+{
+	if (initialized)
+		return 0;
+
+	ipmi_hardcode_init();
+
+	pr_info("IPMI System Interface driver\n");
+
+	ipmi_si_platform_init();
+
+	ipmi_si_pci_init();
+
+	ipmi_si_ls2k_init();
+
+	ipmi_si_parisc_init();
+
+	if (IS_ENABLED(CONFIG_IPMI_SI_ASYNC_INIT)) {
+		async_schedule(async_smi_init, NULL);
+		return 0;
+	}
+
+	return smi_init_scan();
+}
 module_init(init_ipmi_si);
 
 static void wait_msg_processed(struct smi_info *smi_info)
-- 
2.55.0.rc0.799.gd6f94ed593-goog

Re: [PATCH] ipmi:si: Add async init to ipmi_si

[Corey Minyard]

On Thu, Jun 25, 2026 at 05:59:54PM +0200, Michal Clapinski wrote:
> Added a new config option to allow offloading slow part of
> init_ipmi_si. Saves 100ms on my system.

Are you loading as a module or building IPMI into the kernel?

I'm thinking this is a good idea, but not quite done this way.

I have another long-standing issue that if a BMC is not operational when
the system comes up, it will not continue to try to bring it up, so
you have to reboot or hotmod the device in when it becomes available.

I'm thinking that instead of pushing off the whole process, push off
just the individual calls to try_smi_init().  I'm assuming that's where
all the time is spent at init.

So with that it would be possible to periodically retry a BMC until
it eventually comes up.

Plus, that way the "unload_when_empty" function won't be broken with
this feature.

I am also not quite sure what will happen if you try to unload the
module if things are pushed off in a startup state like this.

I'm also not quite sure how this will affect the ACPI IPMI functions in
the kernel.  I would guess it's ok, since it registers to know when the
interface becomes available, but it might be delayed a bit which might
confuse things.  Also, it might delay the driver being available til
later at startup, which may confuse userland users.

I'm also wondering if making this an option makes sense, or if this
should be the way it always works.  An option might be nice if it broke
things, I guess.  But almost everyone uses modules, and that will be
delayed from boot, anyway.  I guess that means ACPI is not an issue,
either.

Just kind of pondering this right now.

-corey

> 
> Signed-off-by: Michal Clapinski <mclapinski@google.com>
> ---
>  drivers/char/ipmi/Kconfig        |  8 ++++++
>  drivers/char/ipmi/ipmi_si_intf.c | 48 +++++++++++++++++++++-----------
>  2 files changed, 40 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> index 669f76000197..8419409dc3b9 100644
> --- a/drivers/char/ipmi/Kconfig
> +++ b/drivers/char/ipmi/Kconfig
> @@ -67,6 +67,14 @@ config IPMI_SI
>  	  Currently, only KCS and SMIC are supported.  If
>  	  you are using IPMI, you should probably say "y" here.
>  
> +config IPMI_SI_ASYNC_INIT
> +	bool 'Asynchronous initialization of IPMI System Interface'
> +	depends on IPMI_SI
> +	default n
> +	help
> +	  Enables asynchronous init of the IPMI System Interface.
> +	  It speeds up the boot time.
> +
>  config IPMI_SSIF
>  	tristate 'IPMI SMBus handler (SSIF)'
>  	depends on I2C
> diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> index 9a9d12be9bf7..3e422c7df60a 100644
> --- a/drivers/char/ipmi/ipmi_si_intf.c
> +++ b/drivers/char/ipmi/ipmi_si_intf.c
> @@ -39,6 +39,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/ipmi.h>
>  #include <linux/ipmi_smi.h>
> +#include <linux/async.h>
>  #include "ipmi_si.h"
>  #include "ipmi_si_sm.h"
>  #include <linux/string.h>
> @@ -2174,25 +2175,10 @@ static bool __init ipmi_smi_info_same(struct smi_info *e1, struct smi_info *e2)
>  		e1->io.addr_data == e2->io.addr_data);
>  }
>  
> -static int __init init_ipmi_si(void)
> +static int __init smi_init_scan(void)
>  {
>  	struct smi_info *e, *e2;
>  
> -	if (initialized)
> -		return 0;
> -
> -	ipmi_hardcode_init();
> -
> -	pr_info("IPMI System Interface driver\n");
> -
> -	ipmi_si_platform_init();
> -
> -	ipmi_si_pci_init();
> -
> -	ipmi_si_ls2k_init();
> -
> -	ipmi_si_parisc_init();
> -
>  	mutex_lock(&smi_infos_lock);
>  
>  	/*
> @@ -2271,6 +2257,36 @@ static int __init init_ipmi_si(void)
>  		return 0;
>  	}
>  }
> +
> +static void __init async_smi_init(void *data, async_cookie_t cookie)
> +{
> +	smi_init_scan();
> +}
> +
> +static int __init init_ipmi_si(void)
> +{
> +	if (initialized)
> +		return 0;
> +
> +	ipmi_hardcode_init();
> +
> +	pr_info("IPMI System Interface driver\n");
> +
> +	ipmi_si_platform_init();
> +
> +	ipmi_si_pci_init();
> +
> +	ipmi_si_ls2k_init();
> +
> +	ipmi_si_parisc_init();
> +
> +	if (IS_ENABLED(CONFIG_IPMI_SI_ASYNC_INIT)) {
> +		async_schedule(async_smi_init, NULL);
> +		return 0;
> +	}
> +
> +	return smi_init_scan();
> +}
>  module_init(init_ipmi_si);
>  
>  static void wait_msg_processed(struct smi_info *smi_info)
> -- 
> 2.55.0.rc0.799.gd6f94ed593-goog
> 

Re: [PATCH] ipmi:si: Add async init to ipmi_si

[Michał Cłapiński]

On Fri, Jun 26, 2026 at 6:35 AM Corey Minyard <corey@minyard.net> wrote:
>
> On Thu, Jun 25, 2026 at 05:59:54PM +0200, Michal Clapinski wrote:
> > Added a new config option to allow offloading slow part of
> > init_ipmi_si. Saves 100ms on my system.
>
> Are you loading as a module or building IPMI into the kernel?

Building in. I don't know much about IPMI but my system won't boot
without it because it can't find the disk. I think some storage
controllers need IPMI?

> I'm thinking this is a good idea, but not quite done this way.
>
> I have another long-standing issue that if a BMC is not operational when
> the system comes up, it will not continue to try to bring it up, so
> you have to reboot or hotmod the device in when it becomes available.
>
> I'm thinking that instead of pushing off the whole process, push off
> just the individual calls to try_smi_init().  I'm assuming that's where
> all the time is spent at init.

I can implement it this way in v2.

> So with that it would be possible to periodically retry a BMC until
> it eventually comes up.
>
> Plus, that way the "unload_when_empty" function won't be broken with
> this feature.
>
> I am also not quite sure what will happen if you try to unload the
> module if things are pushed off in a startup state like this.
>
> I'm also not quite sure how this will affect the ACPI IPMI functions in
> the kernel.  I would guess it's ok, since it registers to know when the
> interface becomes available, but it might be delayed a bit which might
> confuse things.  Also, it might delay the driver being available til
> later at startup, which may confuse userland users.
>
> I'm also wondering if making this an option makes sense, or if this
> should be the way it always works.  An option might be nice if it broke
> things, I guess.  But almost everyone uses modules, and that will be
> delayed from boot, anyway.  I guess that means ACPI is not an issue,
> either.

Since my system won't boot without IPMI, it would probably also fail
the same way if IPMI was still initializing so I didn't want to break
unsuspecting users. In reality it probably wouldn't happen often since
IPMI initialization is fast enough to finish before the rest of the
kernel.

> Just kind of pondering this right now.
>
> -corey
>
> >
> > Signed-off-by: Michal Clapinski <mclapinski@google.com>
> > ---
> >  drivers/char/ipmi/Kconfig        |  8 ++++++
> >  drivers/char/ipmi/ipmi_si_intf.c | 48 +++++++++++++++++++++-----------
> >  2 files changed, 40 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> > index 669f76000197..8419409dc3b9 100644
> > --- a/drivers/char/ipmi/Kconfig
> > +++ b/drivers/char/ipmi/Kconfig
> > @@ -67,6 +67,14 @@ config IPMI_SI
> >         Currently, only KCS and SMIC are supported.  If
> >         you are using IPMI, you should probably say "y" here.
> >
> > +config IPMI_SI_ASYNC_INIT
> > +     bool 'Asynchronous initialization of IPMI System Interface'
> > +     depends on IPMI_SI
> > +     default n
> > +     help
> > +       Enables asynchronous init of the IPMI System Interface.
> > +       It speeds up the boot time.
> > +
> >  config IPMI_SSIF
> >       tristate 'IPMI SMBus handler (SSIF)'
> >       depends on I2C
> > diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> > index 9a9d12be9bf7..3e422c7df60a 100644
> > --- a/drivers/char/ipmi/ipmi_si_intf.c
> > +++ b/drivers/char/ipmi/ipmi_si_intf.c
> > @@ -39,6 +39,7 @@
> >  #include <linux/rcupdate.h>
> >  #include <linux/ipmi.h>
> >  #include <linux/ipmi_smi.h>
> > +#include <linux/async.h>
> >  #include "ipmi_si.h"
> >  #include "ipmi_si_sm.h"
> >  #include <linux/string.h>
> > @@ -2174,25 +2175,10 @@ static bool __init ipmi_smi_info_same(struct smi_info *e1, struct smi_info *e2)
> >               e1->io.addr_data == e2->io.addr_data);
> >  }
> >
> > -static int __init init_ipmi_si(void)
> > +static int __init smi_init_scan(void)
> >  {
> >       struct smi_info *e, *e2;
> >
> > -     if (initialized)
> > -             return 0;
> > -
> > -     ipmi_hardcode_init();
> > -
> > -     pr_info("IPMI System Interface driver\n");
> > -
> > -     ipmi_si_platform_init();
> > -
> > -     ipmi_si_pci_init();
> > -
> > -     ipmi_si_ls2k_init();
> > -
> > -     ipmi_si_parisc_init();
> > -
> >       mutex_lock(&smi_infos_lock);
> >
> >       /*
> > @@ -2271,6 +2257,36 @@ static int __init init_ipmi_si(void)
> >               return 0;
> >       }
> >  }
> > +
> > +static void __init async_smi_init(void *data, async_cookie_t cookie)
> > +{
> > +     smi_init_scan();
> > +}
> > +
> > +static int __init init_ipmi_si(void)
> > +{
> > +     if (initialized)
> > +             return 0;
> > +
> > +     ipmi_hardcode_init();
> > +
> > +     pr_info("IPMI System Interface driver\n");
> > +
> > +     ipmi_si_platform_init();
> > +
> > +     ipmi_si_pci_init();
> > +
> > +     ipmi_si_ls2k_init();
> > +
> > +     ipmi_si_parisc_init();
> > +
> > +     if (IS_ENABLED(CONFIG_IPMI_SI_ASYNC_INIT)) {
> > +             async_schedule(async_smi_init, NULL);
> > +             return 0;
> > +     }
> > +
> > +     return smi_init_scan();
> > +}
> >  module_init(init_ipmi_si);
> >
> >  static void wait_msg_processed(struct smi_info *smi_info)
> > --
> > 2.55.0.rc0.799.gd6f94ed593-goog
> >