[PATCH net] Revert "mdio_bus: Remove unneeded gpiod NULL check"

This reverts commit 95b80bf3db03c2bf572a357cf74b9a6aefef0a4a ("mdio_bus:
Remove unneeded gpiod NULL check"), this commit assumed that GPIOLIB
checks for NULL descriptors, so it's safe to drop them, but it is not
when CONFIG_GPIOLIB is disabled in the kernel. If we do call
gpiod_set_value_cansleep() on a GPIO descriptor we will issue warnings
coming from the inline stubs declared in include/linux/gpio/consumer.h.

Fixes: 95b80bf3db03 ("mdio_bus: Remove unneeded gpiod NULL check")
Reported-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/phy/mdio_bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index b6f9fa670168..2df7b62c1a36 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c

@@ -399,7 +399,8 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 	}
 
 	/* Put PHYs in RESET to save power */
-	gpiod_set_value_cansleep(bus->reset_gpiod, 1);
+	if (bus->reset_gpiod)
+		gpiod_set_value_cansleep(bus->reset_gpiod, 1);
 
 	device_del(&bus->dev);
 	return err;

@@ -424,7 +425,8 @@ void mdiobus_unregister(struct mii_bus *bus)
 	}
 
 	/* Put PHYs in RESET to save power */
-	gpiod_set_value_cansleep(bus->reset_gpiod, 1);
+	if (bus->reset_gpiod)
+		gpiod_set_value_cansleep(bus->reset_gpiod, 1);
 
 	device_del(&bus->dev);
 }

-- 
2.9.3

On Sat, Sep 9, 2017 at 12:38 AM, Florian Fainelli [off-list ref] wrote:

This reverts commit 95b80bf3db03c2bf572a357cf74b9a6aefef0a4a ("mdio_bus:
Remove unneeded gpiod NULL check"), this commit assumed that GPIOLIB
checks for NULL descriptors, so it's safe to drop them, but it is not
when CONFIG_GPIOLIB is disabled in the kernel. If we do call
gpiod_set_value_cansleep() on a GPIO descriptor we will issue warnings
coming from the inline stubs declared in include/linux/gpio/consumer.h.

Fixes: 95b80bf3db03 ("mdio_bus: Remove unneeded gpiod NULL check")
Reported-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Yeah I guess you don't wanna have these messages spewing
in the console. :/

But what about simply doing this:

From 150e4f3c1f227c9a4c31bbb48d44220e25b792ec Mon Sep 17 00:00:00 2001

From: Linus Walleij <redacted>
Date: Sat, 9 Sep 2017 01:07:22 +0200
Subject: [PATCH] net: phy: mdio_bus: mandate gpiolib

The core mdio bus unconditionally uses gpiolib APIs to handle
reset lines which results in runtime errors when it is compiled
out. It is not supposed to be possible to stub out gpiolib
like this, the error messages from the stubs are a sign that
something is wrong.

So just select it. Fix some unneeded #includes while we're
at it.

Signed-off-by: Linus Walleij <redacted>
---
 drivers/net/phy/Kconfig    | 1 +
 drivers/net/phy/mdio_bus.c | 2 --
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index a9d16a3af514..b6c5bb9941c3 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig

@@ -4,6 +4,7 @@

 menuconfig MDIO_DEVICE
     tristate "MDIO bus device drivers"
+    select GPIOLIB
     help
       MDIO devices and driver infrastructure code.

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index b6f9fa670168..9c60f87b7209 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c

@@ -22,11 +22,9 @@
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/device.h>
-#include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of_device.h>
 #include <linux/of_mdio.h>
-#include <linux/of_gpio.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/skbuff.h>

-- 
2.13.5

Yours,
Linus Walleij

On 09/08/2017 04:13 PM, Linus Walleij wrote:

On Sat, Sep 9, 2017 at 12:38 AM, Florian Fainelli [off-list ref] wrote:

quoted

This reverts commit 95b80bf3db03c2bf572a357cf74b9a6aefef0a4a ("mdio_bus:
Remove unneeded gpiod NULL check"), this commit assumed that GPIOLIB
checks for NULL descriptors, so it's safe to drop them, but it is not
when CONFIG_GPIOLIB is disabled in the kernel. If we do call
gpiod_set_value_cansleep() on a GPIO descriptor we will issue warnings
coming from the inline stubs declared in include/linux/gpio/consumer.h.

Fixes: 95b80bf3db03 ("mdio_bus: Remove unneeded gpiod NULL check")
Reported-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Yeah I guess you don't wanna have these messages spewing
in the console. :/

But what about simply doing this:

That would create another dependency which really does not need to be
there as it really prevents you from testing more configurations,
including but not limited to having CONFIG_GPIOLIB=n w/
CONFIG_MDIO_DEVICE=[ym].

The GPIOLIB=n inline stubs have a "contract" with the code calling them
that is fairly clear, which is what this revert is leveraging.

Instead of doing what you suggest, we could also encapsulate the
offending code within an #IS_ENABLED(CONFIG_GPIOLIB) block, which would
be virtually the same thing in terms of object code generated, but would
make it clear there is a functional dependency, I would personally be
keener on that approach than having a select or depends.

Thanks

-- 
Florian

On Sat, Sep 9, 2017 at 1:18 AM, Florian Fainelli [off-list ref] wrote:

On 09/08/2017 04:13 PM, Linus Walleij wrote:

quoted

On Sat, Sep 9, 2017 at 12:38 AM, Florian Fainelli [off-list ref] wrote:

quoted

This reverts commit 95b80bf3db03c2bf572a357cf74b9a6aefef0a4a ("mdio_bus:
Remove unneeded gpiod NULL check"), this commit assumed that GPIOLIB
checks for NULL descriptors, so it's safe to drop them, but it is not
when CONFIG_GPIOLIB is disabled in the kernel. If we do call
gpiod_set_value_cansleep() on a GPIO descriptor we will issue warnings
coming from the inline stubs declared in include/linux/gpio/consumer.h.

Fixes: 95b80bf3db03 ("mdio_bus: Remove unneeded gpiod NULL check")
Reported-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Yeah I guess you don't wanna have these messages spewing
in the console. :/

But what about simply doing this:

That would create another dependency which really does not need to be
there as it really prevents you from testing more configurations,
including but not limited to having CONFIG_GPIOLIB=n w/
CONFIG_MDIO_DEVICE=[ym].

The GPIOLIB=n inline stubs have a "contract" with the code calling them
that is fairly clear, which is what this revert is leveraging.

Ayeah the contract is something like "you can call us if compiled out,
but then you get warnings".

Yeah NULL checks does the trick as well as #ifdef:in in that sense.
It's no big deal so if you prefer this:
Acked-by: Linus Walleij <redacted>

Yours,
Linus Walleij

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Fri,  8 Sep 2017 15:38:07 -0700

This reverts commit 95b80bf3db03c2bf572a357cf74b9a6aefef0a4a ("mdio_bus:
Remove unneeded gpiod NULL check"), this commit assumed that GPIOLIB
checks for NULL descriptors, so it's safe to drop them, but it is not
when CONFIG_GPIOLIB is disabled in the kernel. If we do call
gpiod_set_value_cansleep() on a GPIO descriptor we will issue warnings
coming from the inline stubs declared in include/linux/gpio/consumer.h.

Fixes: 95b80bf3db03 ("mdio_bus: Remove unneeded gpiod NULL check")
Reported-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Applied.