[PATCH] gpio: pinctrl: Initialize Armada-XP GPIO/Pinctrl drivers at arch_initcall

[PATCH] gpio: pinctrl: Initialize Armada-XP GPIO/Pinctrl drivers at arch_initcall

[Joshua Scott]

The Armada-XP contains a set of GPIO pins. These pins may be used to take
other hardware out of reset. However, the drivers used are currently not
initialized until quite late in the boot process (module_platform_driver).

This patch replaces the use of module_platform_driver with arch_initcall
in the two drivers that are used to control the GPIO pins. This allows for
drivers using subsys_initcall or later to access to the pins.


Signed-off-by: Joshua Scott <joshua.scott@alliedtelesis.co.nz>
---
 drivers/gpio/gpio-mvebu.c                 | 13 ++++++++++++-
 drivers/pinctrl/mvebu/pinctrl-armada-xp.c | 12 +++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index 1a54205..3dd7e23 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -860,4 +860,15 @@ static struct platform_driver mvebu_gpio_driver = {
 	.suspend        = mvebu_gpio_suspend,
 	.resume         = mvebu_gpio_resume,
 };
-module_platform_driver(mvebu_gpio_driver);
+
+static int __init mvebu_gpio_driver_init(void)
+{
+	return platform_driver_register(&mvebu_gpio_driver);
+}
+arch_initcall(mvebu_gpio_driver_init);
+
+static void __exit mvebu_gpio_driver_exit(void)
+{
+	platform_driver_unregister(&mvebu_gpio_driver);
+}
+module_exit(mvebu_gpio_driver_exit);
diff --git a/drivers/pinctrl/mvebu/pinctrl-armada-xp.c b/drivers/pinctrl/mvebu/pinctrl-armada-xp.c
index 578db9f..609c732 100644
--- a/drivers/pinctrl/mvebu/pinctrl-armada-xp.c
+++ b/drivers/pinctrl/mvebu/pinctrl-armada-xp.c
@@ -518,7 +518,17 @@ static struct platform_driver armada_xp_pinctrl_driver = {
 	.resume = armada_xp_pinctrl_resume,
 };
 
-module_platform_driver(armada_xp_pinctrl_driver);
+static int __init armada_xp_pinctrl_init(void)
+{
+	return platform_driver_register(&armada_xp_pinctrl_driver);
+}
+arch_initcall(armada_xp_pinctrl_init);
+
+static void __exit armada_xp_pinctrl_exit(void)
+{
+	platform_driver_unregister(&armada_xp_pinctrl_driver);
+}
+module_exit(armada_xp_pinctrl_exit);
 
 MODULE_AUTHOR("Thomas Petazzoni <thomas.petazzoni@free-electrons.com>");
 MODULE_DESCRIPTION("Marvell Armada XP pinctrl driver");
-- 
1.9.1

Re: [PATCH] gpio: pinctrl: Initialize Armada-XP GPIO/Pinctrl drivers at arch_initcall

[Thomas Petazzoni]

Dear Joshua Scott,

On Tue, 12 May 2015 14:39:42 +1200, Joshua Scott wrote:
> The Armada-XP contains a set of GPIO pins. These pins may be used to take
> other hardware out of reset. However, the drivers used are currently not
> initialized until quite late in the boot process (module_platform_driver).
> 
> This patch replaces the use of module_platform_driver with arch_initcall
> in the two drivers that are used to control the GPIO pins. This allows for
> drivers using subsys_initcall or later to access to the pins.
> 
> 
> Signed-off-by: Joshua Scott <joshua.scott@alliedtelesis.co.nz>

Thanks for the patch. However, this goes exactly in the opposite
direction of commit dd640039e8de4135fd59d4d963487d1239d6fabe ("gpio:
mvebu: Remove initcall-based driver initialization"), which switched
from postcore_initcall() to module_platform_driver().

Can you describe which drivers registered at subsys_initcall() need
those GPIOs? We should be able to get around by using deferred probing.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Re: [PATCH] gpio: pinctrl: Initialize Armada-XP GPIO/Pinctrl drivers at arch_initcall

[Joshua Scott]

Hi Thomas,

The driver I'm using that requires access to the GPIO pins is one that 
I've been working on. It doesn't do much, just drives a single reset 
line to take other hardware out of reset.

The hardware that gets taken out of reset includes a few i2c GPIO 
expanders. The GPIO expanders use the gpio-pca953x.c driver, which uses 
subsys_initcall.

One of the things that we found strange: With the code the way it 
currently is, we have access to external GPIO expanders before we were 
able to access the CPUs own built-in GPIO pins.


Thank you,
Joshua Scott

On 12/05/15 19:18, Thomas Petazzoni wrote:
> Dear Joshua Scott,
>
> On Tue, 12 May 2015 14:39:42 +1200, Joshua Scott wrote:
>> The Armada-XP contains a set of GPIO pins. These pins may be used to take
>> other hardware out of reset. However, the drivers used are currently not
>> initialized until quite late in the boot process (module_platform_driver).
>>
>> This patch replaces the use of module_platform_driver with arch_initcall
>> in the two drivers that are used to control the GPIO pins. This allows for
>> drivers using subsys_initcall or later to access to the pins.
>>
>>
>> Signed-off-by: Joshua Scott <joshua.scott@alliedtelesis.co.nz>
> Thanks for the patch. However, this goes exactly in the opposite
> direction of commit dd640039e8de4135fd59d4d963487d1239d6fabe ("gpio:
> mvebu: Remove initcall-based driver initialization"), which switched
> from postcore_initcall() to module_platform_driver().
>
> Can you describe which drivers registered at subsys_initcall() need
> those GPIOs? We should be able to get around by using deferred probing.
>
> Thanks,
>
> Thomas

Re: [PATCH] gpio: pinctrl: Initialize Armada-XP GPIO/Pinctrl drivers at arch_initcall

[Thomas Petazzoni]

Joshua,

On Tue, 12 May 2015 22:29:54 +0000, Joshua Scott wrote:

> The driver I'm using that requires access to the GPIO pins is one that 
> I've been working on. It doesn't do much, just drives a single reset 
> line to take other hardware out of reset.
> 
> The hardware that gets taken out of reset includes a few i2c GPIO 
> expanders. The GPIO expanders use the gpio-pca953x.c driver, which uses 
> subsys_initcall.
> 
> One of the things that we found strange: With the code the way it 
> currently is, we have access to external GPIO expanders before we were 
> able to access the CPUs own built-in GPIO pins.

To be honest, it is not very clear (at least to me) what is the policy
of the GPIO subsystem in terms of initialization order. Why is this
gpio-pca953x.c driver using subsys_initcall() instead of the regular
module_i2c_driver() call, which is for example used by gpio-adnp.c or
gpio-adp5588.c.

Linus, do you have any comments/suggestions about this?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com