[PATCH v1 0/2] Fix console probe delay due to fw_devlink

[PATCH v1 0/2] Fix console probe delay due to fw_devlink

[Saravana Kannan]

fw_devlink.strict=1 has been enabled by default. This was delaying the
probe of console devices. This series fixes that.

Sasha/Peng,

Can you test this please?

-Saravana

Cc: Sascha Hauer <sha@pengutronix.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Kevin Hilman <khilman@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: David Ahern <dsahern@kernel.org>
Cc: kernel-team@android.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: iommu@lists.linux-foundation.org
Cc: netdev@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Cc: kernel@pengutronix.de

Saravana Kannan (2):
  driver core: fw_devlink: Allow firmware to mark devices as best effort
  of: base: Avoid console probe delay when fw_devlink.strict=1

 drivers/base/core.c    | 3 ++-
 drivers/of/base.c      | 2 ++
 include/linux/fwnode.h | 4 ++++
 3 files changed, 8 insertions(+), 1 deletion(-)

-- 
2.37.0.rc0.161.g10f37bed90-goog

[PATCH v1 1/2] driver core: fw_devlink: Allow firmware to mark devices as best effort

[Saravana Kannan]

When firmware sets the FWNODE_FLAG_BEST_EFFORT flag for a fwnode,
fw_devlink will do a best effort ordering for that device where it'll
only enforce the probe/suspend/resume ordering of that device with
suppliers that have drivers. The driver of that device can then decide
if it wants to defer probe or probe without the suppliers.

This will be useful for avoid probe delays of the console device that
were caused by commit 71066545b48e ("driver core: Set
fw_devlink.strict=1 by default").

Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
Reported-by: Sascha Hauer <sha@pengutronix.de>
Reported-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/base/core.c    | 3 ++-
 include/linux/fwnode.h | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 839f64485a55..61edd18b7bf3 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -968,7 +968,8 @@ static void device_links_missing_supplier(struct device *dev)
 
 static bool dev_is_best_effort(struct device *dev)
 {
-	return fw_devlink_best_effort && dev->can_match;
+	return (fw_devlink_best_effort && dev->can_match) ||
+		dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT;
 }
 
 /**
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 9a81c4410b9f..89b9bdfca925 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -27,11 +27,15 @@ struct device;
  *			     driver needs its child devices to be bound with
  *			     their respective drivers as soon as they are
  *			     added.
+ * BEST_EFFORT: The fwnode/device needs to probe early and might be missing some
+ *		suppliers. Only enforce ordering with suppliers that have
+ *		drivers.
  */
 #define FWNODE_FLAG_LINKS_ADDED			BIT(0)
 #define FWNODE_FLAG_NOT_DEVICE			BIT(1)
 #define FWNODE_FLAG_INITIALIZED			BIT(2)
 #define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD	BIT(3)
+#define FWNODE_FLAG_BEST_EFFORT			BIT(4)
 
 struct fwnode_handle {
 	struct fwnode_handle *secondary;
-- 
2.37.0.rc0.161.g10f37bed90-goog

[PATCH v1 2/2] of: base: Avoid console probe delay when fw_devlink.strict=1

[Saravana Kannan]

Commit 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
enabled iommus and dmas dependency enforcement by default. On some
systems, this caused the console device's probe to get delayed until the
deferred_probe_timeout expires.

We need consoles to work as soon as possible, so mark the console device
node with FWNODE_FLAG_BEST_EFFORT so that fw_delink knows not to delay
the probe of the console device for suppliers without drivers. The
driver can then make the decision on where it can probe without those
suppliers or defer its probe.

Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
Reported-by: Sascha Hauer <sha@pengutronix.de>
Reported-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/of/base.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d4f98c8469ed..a19cd0c73644 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1919,6 +1919,8 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
 			of_property_read_string(of_aliases, "stdout", &name);
 		if (name)
 			of_stdout = of_find_node_opts_by_path(name, &of_stdout_options);
+		if (of_stdout)
+			of_stdout->fwnode.flags |= FWNODE_FLAG_BEST_EFFORT;
 	}
 
 	if (!of_aliases)
-- 
2.37.0.rc0.161.g10f37bed90-goog

RE: [PATCH v1 0/2] Fix console probe delay due to fw_devlink

[Peng Fan]

> Subject: [PATCH v1 0/2] Fix console probe delay due to fw_devlink
> 
> fw_devlink.strict=1 has been enabled by default. This was delaying the probe
> of console devices. This series fixes that.
> 
> Sasha/Peng,
> 
> Can you test this please?

Thanks, just give a test on i.MX8MP-EVK, works well now.

Tested-by: Peng Fan <peng.fan@nxp.com> #i.MX8MP-EVK

Thanks,
Peng.

> 
> -Saravana
> 
> Cc: Sascha Hauer <sha@pengutronix.de>
> Cc: Peng Fan <peng.fan@nxp.com>
> Cc: Kevin Hilman <khilman@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Andrew Lunn <andrew@lunn.ch>
> Cc: Heiner Kallweit <hkallweit1@gmail.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
> Cc: David Ahern <dsahern@kernel.org>
> Cc: kernel-team@android.com
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-pm@vger.kernel.org
> Cc: iommu@lists.linux-foundation.org
> Cc: netdev@vger.kernel.org
> Cc: linux-gpio@vger.kernel.org
> Cc: kernel@pengutronix.de
> 
> Saravana Kannan (2):
>   driver core: fw_devlink: Allow firmware to mark devices as best effort
>   of: base: Avoid console probe delay when fw_devlink.strict=1
> 
>  drivers/base/core.c    | 3 ++-
>  drivers/of/base.c      | 2 ++
>  include/linux/fwnode.h | 4 ++++
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> --
> 2.37.0.rc0.161.g10f37bed90-goog

Re: [PATCH v1 0/2] Fix console probe delay due to fw_devlink

[Saravana Kannan]

On Wed, Jun 22, 2022 at 3:32 PM Peng Fan <peng.fan@nxp.com> wrote:
>
> > Subject: [PATCH v1 0/2] Fix console probe delay due to fw_devlink
> >
> > fw_devlink.strict=1 has been enabled by default. This was delaying the probe
> > of console devices. This series fixes that.
> >
> > Sasha/Peng,
> >
> > Can you test this please?
>
> Thanks, just give a test on i.MX8MP-EVK, works well now.
>
> Tested-by: Peng Fan <peng.fan@nxp.com> #i.MX8MP-EVK

Lol, that was quick! Thanks!

-Saravana

>
> Thanks,
> Peng.
>
> >
> > -Saravana
> >
> > Cc: Sascha Hauer <sha@pengutronix.de>
> > Cc: Peng Fan <peng.fan@nxp.com>
> > Cc: Kevin Hilman <khilman@kernel.org>
> > Cc: Ulf Hansson <ulf.hansson@linaro.org>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: Pavel Machek <pavel@ucw.cz>
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Andrew Lunn <andrew@lunn.ch>
> > Cc: Heiner Kallweit <hkallweit1@gmail.com>
> > Cc: Russell King <linux@armlinux.org.uk>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: Eric Dumazet <edumazet@google.com>
> > Cc: Jakub Kicinski <kuba@kernel.org>
> > Cc: Paolo Abeni <pabeni@redhat.com>
> > Cc: Linus Walleij <linus.walleij@linaro.org>
> > Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
> > Cc: David Ahern <dsahern@kernel.org>
> > Cc: kernel-team@android.com
> > Cc: linux-kernel@vger.kernel.org
> > Cc: linux-pm@vger.kernel.org
> > Cc: iommu@lists.linux-foundation.org
> > Cc: netdev@vger.kernel.org
> > Cc: linux-gpio@vger.kernel.org
> > Cc: kernel@pengutronix.de
> >
> > Saravana Kannan (2):
> >   driver core: fw_devlink: Allow firmware to mark devices as best effort
> >   of: base: Avoid console probe delay when fw_devlink.strict=1
> >
> >  drivers/base/core.c    | 3 ++-
> >  drivers/of/base.c      | 2 ++
> >  include/linux/fwnode.h | 4 ++++
> >  3 files changed, 8 insertions(+), 1 deletion(-)
> >
> > --
> > 2.37.0.rc0.161.g10f37bed90-goog
>

Re: [PATCH v1 1/2] driver core: fw_devlink: Allow firmware to mark devices as best effort

[Sascha Hauer]

On Wed, Jun 22, 2022 at 02:59:10PM -0700, Saravana Kannan wrote:
> When firmware sets the FWNODE_FLAG_BEST_EFFORT flag for a fwnode,
> fw_devlink will do a best effort ordering for that device where it'll
> only enforce the probe/suspend/resume ordering of that device with
> suppliers that have drivers. The driver of that device can then decide
> if it wants to defer probe or probe without the suppliers.
> 
> This will be useful for avoid probe delays of the console device that
> were caused by commit 71066545b48e ("driver core: Set
> fw_devlink.strict=1 by default").
> 
> Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
> Reported-by: Sascha Hauer <sha@pengutronix.de>
> Reported-by: Peng Fan <peng.fan@nxp.com>
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/base/core.c    | 3 ++-
>  include/linux/fwnode.h | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 839f64485a55..61edd18b7bf3 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -968,7 +968,8 @@ static void device_links_missing_supplier(struct device *dev)
>  
>  static bool dev_is_best_effort(struct device *dev)
>  {
> -	return fw_devlink_best_effort && dev->can_match;
> +	return (fw_devlink_best_effort && dev->can_match) ||
> +		dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT;

Check for dev->fwnode first. I am running in a NULL pointer exception
here for a device that doesn't have a fwnode.

Sascha


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Re: [PATCH v1 1/2] driver core: fw_devlink: Allow firmware to mark devices as best effort

[Saravana Kannan]

On Wed, Jun 22, 2022 at 11:50 PM Sascha Hauer <sha@pengutronix.de> wrote:
>
> On Wed, Jun 22, 2022 at 02:59:10PM -0700, Saravana Kannan wrote:
> > When firmware sets the FWNODE_FLAG_BEST_EFFORT flag for a fwnode,
> > fw_devlink will do a best effort ordering for that device where it'll
> > only enforce the probe/suspend/resume ordering of that device with
> > suppliers that have drivers. The driver of that device can then decide
> > if it wants to defer probe or probe without the suppliers.
> >
> > This will be useful for avoid probe delays of the console device that
> > were caused by commit 71066545b48e ("driver core: Set
> > fw_devlink.strict=1 by default").
> >
> > Fixes: 71066545b48e ("driver core: Set fw_devlink.strict=1 by default")
> > Reported-by: Sascha Hauer <sha@pengutronix.de>
> > Reported-by: Peng Fan <peng.fan@nxp.com>
> > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > ---
> >  drivers/base/core.c    | 3 ++-
> >  include/linux/fwnode.h | 4 ++++
> >  2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index 839f64485a55..61edd18b7bf3 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -968,7 +968,8 @@ static void device_links_missing_supplier(struct device *dev)
> >
> >  static bool dev_is_best_effort(struct device *dev)
> >  {
> > -     return fw_devlink_best_effort && dev->can_match;
> > +     return (fw_devlink_best_effort && dev->can_match) ||
> > +             dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT;
>
> Check for dev->fwnode first. I am running in a NULL pointer exception
> here for a device that doesn't have a fwnode.

Oops. Fixed and sent out a v2.

-Saravana