[PATCH 0/7] driver core: prevent deferred probe with platform_driver_probe

[PATCH 0/7] driver core: prevent deferred probe with platform_driver_probe

[Johan Hovold]

Deferred probing cannot be used with platform_driver_probe as by the
time probing is retried either the driver has been unregistered or its
probe function has been set to platform_drv_probe_fail.

With commit e9354576 ("gpiolib: Defer failed gpio requests by default")
the gpio subsystem started returning -EPROBE_DEFER, which in turn
several platform drivers using platform_driver_probe return to driver
core. Other subsystems (e.g. regulator) has since started doing the
same.

The first patch in this series prevents platform drivers using
platform_driver_probe from requesting probe deferral while warning that
it is not supported.

The remaining patches move six platform-driver probe functions that rely
on gpio_request out of __init. There are likely other probe functions
that might return -EPROBE_DEFER and should be moved out of __init as
well.

Note that the mvsdio, at91_cf and pxa25x_udc patches are completely
untested.

Johan


Johan Hovold (7):
  driver core: prevent deferred probe with platform_driver_probe
  mmc: mvsdio: fix deferred probe from __init
  mtd: atmel_nand: fix deferred probe from __init
  pcmcia: at91_cf: fix deferred probe from __init
  usb: gadget: pxa25x_udc: fix deferred probe from __init
  usb: phy: gpio-vbus: fix deferred probe from __init
  backlight: atmel-pwm-bl: fix deferred probe from __init

 drivers/base/platform.c                | 17 +++++++++++++----
 drivers/mmc/host/mvsdio.c              | 11 ++++++-----
 drivers/mtd/nand/atmel_nand.c          | 13 +++++++------
 drivers/pcmcia/at91_cf.c               | 11 +++++------
 drivers/usb/gadget/pxa25x_udc.c        |  9 +++++----
 drivers/usb/phy/phy-gpio-vbus-usb.c    | 11 +++++------
 drivers/video/backlight/atmel-pwm-bl.c |  9 +++++----
 include/linux/platform_device.h        |  1 +
 8 files changed, 47 insertions(+), 35 deletions(-)

-- 
1.8.3.2

[PATCH 1/7] driver core: prevent deferred probe with platform_driver_probe

[Johan Hovold]

Prevent drivers relying on platform_driver_probe from requesting
deferred probing in order to avoid further futile probe attempts (either
the driver has been unregistered or its probe function has been set to
platform_drv_probe_fail when probing is retried).

Note that several platform drivers currently return subsystem errors
from probe and that these can include -EPROBE_DEFER (e.g. if a gpio
request fails).

Add a warning to platform_drv_probe that can be used to catch drivers
that inadvertently request probe deferral while using
platform_driver_probe.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/base/platform.c         | 17 +++++++++++++----
 include/linux/platform_device.h |  1 +
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 4f8bef3..47051cd 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -488,6 +488,11 @@ static int platform_drv_probe(struct device *_dev)
 	if (ret && ACPI_HANDLE(_dev))
 		acpi_dev_pm_detach(_dev, true);
 
+	if (drv->prevent_deferred_probe && ret = -EPROBE_DEFER) {
+		dev_warn(_dev, "probe deferral not supported\n");
+		ret = -ENXIO;
+	}
+
 	return ret;
 }
 
@@ -553,8 +558,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister);
 /**
  * platform_driver_probe - register driver for non-hotpluggable device
  * @drv: platform driver structure
- * @probe: the driver probe routine, probably from an __init section,
- *         must not return -EPROBE_DEFER.
+ * @probe: the driver probe routine, probably from an __init section
  *
  * Use this instead of platform_driver_register() when you know the device
  * is not hotpluggable and has already been registered, and you want to
@@ -565,8 +569,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister);
  * into system-on-chip processors, where the controller devices have been
  * configured as part of board setup.
  *
- * This is incompatible with deferred probing so probe() must not
- * return -EPROBE_DEFER.
+ * Note that this is incompatible with deferred probing.
  *
  * Returns zero if the driver registered and bound to a device, else returns
  * a negative error code and with the driver not registered.
@@ -576,6 +579,12 @@ int __init_or_module platform_driver_probe(struct platform_driver *drv,
 {
 	int retval, code;
 
+	/*
+	 * Prevent driver from requesting probe deferral to avoid further
+	 * futile probe attempts.
+	 */
+	drv->prevent_deferred_probe = true;
+
 	/* make sure driver won't have bind/unbind attributes */
 	drv->driver.suppress_bind_attrs = true;
 
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index ce8e4ff..16f6654 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -178,6 +178,7 @@ struct platform_driver {
 	int (*resume)(struct platform_device *);
 	struct device_driver driver;
 	const struct platform_device_id *id_table;
+	bool prevent_deferred_probe;
 };
 
 #define to_platform_driver(drv)	(container_of((drv), struct platform_driver, \
-- 
1.8.3.2

[PATCH 2/7] mmc: mvsdio: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
this driver might return -EPROBE_DEFER if the mmc_gpio_request_cd fails.

Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Chris Ball <cjb@laptop.org>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/mmc/host/mvsdio.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/mvsdio.c b/drivers/mmc/host/mvsdio.c
index 06c5b0b..deecee0 100644
--- a/drivers/mmc/host/mvsdio.c
+++ b/drivers/mmc/host/mvsdio.c
@@ -655,7 +655,7 @@ static const struct mmc_host_ops mvsd_ops = {
 	.enable_sdio_irq	= mvsd_enable_sdio_irq,
 };
 
-static void __init
+static void
 mv_conf_mbus_windows(struct mvsd_host *host,
 		     const struct mbus_dram_target_info *dram)
 {
@@ -677,7 +677,7 @@ mv_conf_mbus_windows(struct mvsd_host *host,
 	}
 }
 
-static int __init mvsd_probe(struct platform_device *pdev)
+static int mvsd_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct mmc_host *mmc = NULL;
@@ -819,7 +819,7 @@ out:
 	return ret;
 }
 
-static int __exit mvsd_remove(struct platform_device *pdev)
+static int mvsd_remove(struct platform_device *pdev)
 {
 	struct mmc_host *mmc = platform_get_drvdata(pdev);
 
@@ -872,7 +872,8 @@ static const struct of_device_id mvsdio_dt_ids[] = {
 MODULE_DEVICE_TABLE(of, mvsdio_dt_ids);
 
 static struct platform_driver mvsd_driver = {
-	.remove		= __exit_p(mvsd_remove),
+	.probe		= mvsd_probe,
+	.remove		= mvsd_remove,
 	.suspend	= mvsd_suspend,
 	.resume		= mvsd_resume,
 	.driver		= {
@@ -881,7 +882,7 @@ static struct platform_driver mvsd_driver = {
 	},
 };
 
-module_platform_driver_probe(mvsd_driver, mvsd_probe);
+module_platform_driver(mvsd_driver);
 
 /* maximum card clock frequency (default 50MHz) */
 module_param(maxfreq, int, 0);
-- 
1.8.3.2

[PATCH 4/7] pcmcia: at91_cf: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
this driver might return -EPROBE_DEFER if a gpio_request fails.

Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/pcmcia/at91_cf.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/pcmcia/at91_cf.c b/drivers/pcmcia/at91_cf.c
index b8f5acf..de24232 100644
--- a/drivers/pcmcia/at91_cf.c
+++ b/drivers/pcmcia/at91_cf.c
@@ -245,7 +245,7 @@ static int at91_cf_dt_init(struct platform_device *pdev)
 }
 #endif
 
-static int __init at91_cf_probe(struct platform_device *pdev)
+static int at91_cf_probe(struct platform_device *pdev)
 {
 	struct at91_cf_socket	*cf;
 	struct at91_cf_data	*board = pdev->dev.platform_data;
@@ -354,7 +354,7 @@ fail0a:
 	return status;
 }
 
-static int __exit at91_cf_remove(struct platform_device *pdev)
+static int at91_cf_remove(struct platform_device *pdev)
 {
 	struct at91_cf_socket	*cf = platform_get_drvdata(pdev);
 
@@ -404,14 +404,13 @@ static struct platform_driver at91_cf_driver = {
 		.owner		= THIS_MODULE,
 		.of_match_table = of_match_ptr(at91_cf_dt_ids),
 	},
-	.remove		= __exit_p(at91_cf_remove),
+	.probe		= at91_cf_probe,
+	.remove		= at91_cf_remove,
 	.suspend	= at91_cf_suspend,
 	.resume		= at91_cf_resume,
 };
 
-/*--------------------------------------------------------------------------*/
-
-module_platform_driver_probe(at91_cf_driver, at91_cf_probe);
+module_platform_driver(at91_cf_driver);
 
 MODULE_DESCRIPTION("AT91 Compact Flash Driver");
 MODULE_AUTHOR("David Brownell");
-- 
1.8.3.2

Re: [PATCH 4/7] pcmcia: at91_cf: fix deferred probe from __init

[Nicolas Ferre]

On 23/09/2013 16:27, Johan Hovold :
> Move probe out of __init section and don't use platform_driver_probe
> which cannot be used with deferred probing.
>
> Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
> this driver might return -EPROBE_DEFER if a gpio_request fails.
>
> Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> Cc: Nicolas Ferre <nicolas.ferre@atmel.com>

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

Thanks Johan.

> Signed-off-by: Johan Hovold <jhovold@gmail.com>
> ---
>   drivers/pcmcia/at91_cf.c | 11 +++++------
>   1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pcmcia/at91_cf.c b/drivers/pcmcia/at91_cf.c
> index b8f5acf..de24232 100644
> --- a/drivers/pcmcia/at91_cf.c
> +++ b/drivers/pcmcia/at91_cf.c
> @@ -245,7 +245,7 @@ static int at91_cf_dt_init(struct platform_device *pdev)
>   }
>   #endif
>
> -static int __init at91_cf_probe(struct platform_device *pdev)
> +static int at91_cf_probe(struct platform_device *pdev)
>   {
>   	struct at91_cf_socket	*cf;
>   	struct at91_cf_data	*board = pdev->dev.platform_data;
> @@ -354,7 +354,7 @@ fail0a:
>   	return status;
>   }
>
> -static int __exit at91_cf_remove(struct platform_device *pdev)
> +static int at91_cf_remove(struct platform_device *pdev)
>   {
>   	struct at91_cf_socket	*cf = platform_get_drvdata(pdev);
>
> @@ -404,14 +404,13 @@ static struct platform_driver at91_cf_driver = {
>   		.owner		= THIS_MODULE,
>   		.of_match_table = of_match_ptr(at91_cf_dt_ids),
>   	},
> -	.remove		= __exit_p(at91_cf_remove),
> +	.probe		= at91_cf_probe,
> +	.remove		= at91_cf_remove,
>   	.suspend	= at91_cf_suspend,
>   	.resume		= at91_cf_resume,
>   };
>
> -/*--------------------------------------------------------------------------*/
> -
> -module_platform_driver_probe(at91_cf_driver, at91_cf_probe);
> +module_platform_driver(at91_cf_driver);
>
>   MODULE_DESCRIPTION("AT91 Compact Flash Driver");
>   MODULE_AUTHOR("David Brownell");
>


-- 
Nicolas Ferre

[PATCH 3/7] mtd: atmel_nand: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
this driver might return -EPROBE_DEFER if a gpio_request fails.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/mtd/nand/atmel_nand.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 060feea..bd1ce7d 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -1139,7 +1139,7 @@ static int pmecc_choose_ecc(struct atmel_nand_host *host,
 	return 0;
 }
 
-static int __init atmel_pmecc_nand_init_params(struct platform_device *pdev,
+static int atmel_pmecc_nand_init_params(struct platform_device *pdev,
 					 struct atmel_nand_host *host)
 {
 	struct mtd_info *mtd = &host->mtd;
@@ -1548,7 +1548,7 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
 }
 #endif
 
-static int __init atmel_hw_nand_init_params(struct platform_device *pdev,
+static int atmel_hw_nand_init_params(struct platform_device *pdev,
 					 struct atmel_nand_host *host)
 {
 	struct mtd_info *mtd = &host->mtd;
@@ -1987,7 +1987,7 @@ static struct platform_driver atmel_nand_nfc_driver;
 /*
  * Probe for the NAND device.
  */
-static int __init atmel_nand_probe(struct platform_device *pdev)
+static int atmel_nand_probe(struct platform_device *pdev)
 {
 	struct atmel_nand_host *host;
 	struct mtd_info *mtd;
@@ -2184,7 +2184,7 @@ err_nand_ioremap:
 /*
  * Remove a NAND device.
  */
-static int __exit atmel_nand_remove(struct platform_device *pdev)
+static int atmel_nand_remove(struct platform_device *pdev)
 {
 	struct atmel_nand_host *host = platform_get_drvdata(pdev);
 	struct mtd_info *mtd = &host->mtd;
@@ -2270,7 +2270,8 @@ static struct platform_driver atmel_nand_nfc_driver = {
 };
 
 static struct platform_driver atmel_nand_driver = {
-	.remove		= __exit_p(atmel_nand_remove),
+	.probe		= atmel_nand_probe,
+	.remove		= atmel_nand_remove,
 	.driver		= {
 		.name	= "atmel_nand",
 		.owner	= THIS_MODULE,
@@ -2278,7 +2279,7 @@ static struct platform_driver atmel_nand_driver = {
 	},
 };
 
-module_platform_driver_probe(atmel_nand_driver, atmel_nand_probe);
+module_platform_driver(atmel_nand_driver);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Rick Bronson");
-- 
1.8.3.2

[PATCH 5/7] usb: gadget: pxa25x_udc: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
this driver might return -EPROBE_DEFER if a gpio_request fails.

Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/usb/gadget/pxa25x_udc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/pxa25x_udc.c b/drivers/usb/gadget/pxa25x_udc.c
index cc92074..0ac6064 100644
--- a/drivers/usb/gadget/pxa25x_udc.c
+++ b/drivers/usb/gadget/pxa25x_udc.c
@@ -2054,7 +2054,7 @@ static struct pxa25x_udc memory = {
 /*
  *	probe - binds to the platform device
  */
-static int __init pxa25x_udc_probe(struct platform_device *pdev)
+static int pxa25x_udc_probe(struct platform_device *pdev)
 {
 	struct pxa25x_udc *dev = &memory;
 	int retval, irq;
@@ -2203,7 +2203,7 @@ static void pxa25x_udc_shutdown(struct platform_device *_dev)
 	pullup_off();
 }
 
-static int __exit pxa25x_udc_remove(struct platform_device *pdev)
+static int pxa25x_udc_remove(struct platform_device *pdev)
 {
 	struct pxa25x_udc *dev = platform_get_drvdata(pdev);
 
@@ -2294,7 +2294,8 @@ static int pxa25x_udc_resume(struct platform_device *dev)
 
 static struct platform_driver udc_driver = {
 	.shutdown	= pxa25x_udc_shutdown,
-	.remove		= __exit_p(pxa25x_udc_remove),
+	.probe		= pxa25x_udc_probe,
+	.remove		= pxa25x_udc_remove,
 	.suspend	= pxa25x_udc_suspend,
 	.resume		= pxa25x_udc_resume,
 	.driver		= {
@@ -2303,7 +2304,7 @@ static struct platform_driver udc_driver = {
 	},
 };
 
-module_platform_driver_probe(udc_driver, pxa25x_udc_probe);
+module_platform_driver(udc_driver);
 
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_AUTHOR("Frank Becker, Robert Schwebel, David Brownell");
-- 
1.8.3.2

[PATCH 6/7] usb: phy: gpio-vbus: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
and 04bf3011 ("regulator: Support driver probe deferral") this driver
might return -EPROBE_DEFER if a gpio_request or regulator_get fails.

Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/usb/phy/phy-gpio-vbus-usb.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/phy/phy-gpio-vbus-usb.c b/drivers/usb/phy/phy-gpio-vbus-usb.c
index b2f29c9..02799a5 100644
--- a/drivers/usb/phy/phy-gpio-vbus-usb.c
+++ b/drivers/usb/phy/phy-gpio-vbus-usb.c
@@ -241,7 +241,7 @@ static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
 
 /* platform driver interface */
 
-static int __init gpio_vbus_probe(struct platform_device *pdev)
+static int gpio_vbus_probe(struct platform_device *pdev)
 {
 	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
 	struct gpio_vbus_data *gpio_vbus;
@@ -349,7 +349,7 @@ err_gpio:
 	return err;
 }
 
-static int __exit gpio_vbus_remove(struct platform_device *pdev)
+static int gpio_vbus_remove(struct platform_device *pdev)
 {
 	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
 	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
@@ -398,8 +398,6 @@ static const struct dev_pm_ops gpio_vbus_dev_pm_ops = {
 };
 #endif
 
-/* NOTE:  the gpio-vbus device may *NOT* be hotplugged */
-
 MODULE_ALIAS("platform:gpio-vbus");
 
 static struct platform_driver gpio_vbus_driver = {
@@ -410,10 +408,11 @@ static struct platform_driver gpio_vbus_driver = {
 		.pm = &gpio_vbus_dev_pm_ops,
 #endif
 	},
-	.remove  = __exit_p(gpio_vbus_remove),
+	.probe		= gpio_vbus_probe,
+	.remove		= gpio_vbus_remove,
 };
 
-module_platform_driver_probe(gpio_vbus_driver, gpio_vbus_probe);
+module_platform_driver(gpio_vbus_driver);
 
 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
 MODULE_AUTHOR("Philipp Zabel");
-- 
1.8.3.2

[PATCH 7/7] backlight: atmel-pwm-bl: fix deferred probe from __init

[Johan Hovold]

Move probe out of __init section and don't use platform_driver_probe
which cannot be used with deferred probing.

Since commit e9354576 ("gpiolib: Defer failed gpio requests by default")
this driver might return -EPROBE_DEFER if a gpio_request fails.

Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
---
 drivers/video/backlight/atmel-pwm-bl.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c
index 0393d82..f7447f7 100644
--- a/drivers/video/backlight/atmel-pwm-bl.c
+++ b/drivers/video/backlight/atmel-pwm-bl.c
@@ -118,7 +118,7 @@ static const struct backlight_ops atmel_pwm_bl_ops = {
 	.update_status  = atmel_pwm_bl_set_intensity,
 };
 
-static int __init atmel_pwm_bl_probe(struct platform_device *pdev)
+static int atmel_pwm_bl_probe(struct platform_device *pdev)
 {
 	struct backlight_properties props;
 	const struct atmel_pwm_bl_platform_data *pdata;
@@ -202,7 +202,7 @@ err_free_mem:
 	return retval;
 }
 
-static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
+static int atmel_pwm_bl_remove(struct platform_device *pdev)
 {
 	struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
 
@@ -220,10 +220,11 @@ static struct platform_driver atmel_pwm_bl_driver = {
 		.name = "atmel-pwm-bl",
 	},
 	/* REVISIT add suspend() and resume() */
-	.remove = __exit_p(atmel_pwm_bl_remove),
+	.probe = atmel_pwm_bl_probe,
+	.remove = atmel_pwm_bl_remove,
 };
 
-module_platform_driver_probe(atmel_pwm_bl_driver, atmel_pwm_bl_probe);
+module_platform_driver(atmel_pwm_bl_driver);
 
 MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
 MODULE_DESCRIPTION("Atmel PWM backlight driver");
-- 
1.8.3.2

Re: [PATCH 0/7] driver core: prevent deferred probe with platform_driver_probe

[Sascha Hauer]

On Mon, Sep 23, 2013 at 04:27:25PM +0200, Johan Hovold wrote:
> Deferred probing cannot be used with platform_driver_probe as by the
> time probing is retried either the driver has been unregistered or its
> probe function has been set to platform_drv_probe_fail.
> 
> With commit e9354576 ("gpiolib: Defer failed gpio requests by default")
> the gpio subsystem started returning -EPROBE_DEFER, which in turn
> several platform drivers using platform_driver_probe return to driver
> core. Other subsystems (e.g. regulator) has since started doing the
> same.
> 
> The first patch in this series prevents platform drivers using
> platform_driver_probe from requesting probe deferral while warning that
> it is not supported.
> 
> The remaining patches move six platform-driver probe functions that rely
> on gpio_request out of __init. There are likely other probe functions
> that might return -EPROBE_DEFER and should be moved out of __init as
> well.

As usually when I read this I wonder why platform_driver_probe exists
anyway. The only advantage I can think off is that the probe functions
are in __init and thus can be disposed of later. Now you remove the
__init annotations from these probe functions. Wouldn't it be better to
convert the drivers to regular platform_driver_register instead?

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH 0/7] driver core: prevent deferred probe with platform_driver_probe

[Johan Hovold]

On Mon, Sep 23, 2013 at 04:50:29PM +0200, Sascha Hauer wrote:
> On Mon, Sep 23, 2013 at 04:27:25PM +0200, Johan Hovold wrote:
> > Deferred probing cannot be used with platform_driver_probe as by the
> > time probing is retried either the driver has been unregistered or its
> > probe function has been set to platform_drv_probe_fail.
> > 
> > With commit e9354576 ("gpiolib: Defer failed gpio requests by default")
> > the gpio subsystem started returning -EPROBE_DEFER, which in turn
> > several platform drivers using platform_driver_probe return to driver
> > core. Other subsystems (e.g. regulator) has since started doing the
> > same.
> > 
> > The first patch in this series prevents platform drivers using
> > platform_driver_probe from requesting probe deferral while warning that
> > it is not supported.
> > 
> > The remaining patches move six platform-driver probe functions that rely
> > on gpio_request out of __init. There are likely other probe functions
> > that might return -EPROBE_DEFER and should be moved out of __init as
> > well.
> 
> As usually when I read this I wonder why platform_driver_probe exists
> anyway. The only advantage I can think off is that the probe functions
> are in __init and thus can be disposed of later. Now you remove the
> __init annotations from these probe functions. Wouldn't it be better to
> convert the drivers to regular platform_driver_register instead?

Perhaps that paragraph was a bit unclear: I move them out of __init
_and_ use platform_driver_register instead of platform_driver_probe as
well.

Johan

Re: [PATCH 0/7] driver core: prevent deferred probe with platform_driver_probe

[Sascha Hauer]

On Mon, Sep 23, 2013 at 05:20:18PM +0200, Johan Hovold wrote:
> On Mon, Sep 23, 2013 at 04:50:29PM +0200, Sascha Hauer wrote:
> > On Mon, Sep 23, 2013 at 04:27:25PM +0200, Johan Hovold wrote:
> > > Deferred probing cannot be used with platform_driver_probe as by the
> > > time probing is retried either the driver has been unregistered or its
> > > probe function has been set to platform_drv_probe_fail.
> > > 
> > > With commit e9354576 ("gpiolib: Defer failed gpio requests by default")
> > > the gpio subsystem started returning -EPROBE_DEFER, which in turn
> > > several platform drivers using platform_driver_probe return to driver
> > > core. Other subsystems (e.g. regulator) has since started doing the
> > > same.
> > > 
> > > The first patch in this series prevents platform drivers using
> > > platform_driver_probe from requesting probe deferral while warning that
> > > it is not supported.
> > > 
> > > The remaining patches move six platform-driver probe functions that rely
> > > on gpio_request out of __init. There are likely other probe functions
> > > that might return -EPROBE_DEFER and should be moved out of __init as
> > > well.
> > 
> > As usually when I read this I wonder why platform_driver_probe exists
> > anyway. The only advantage I can think off is that the probe functions
> > are in __init and thus can be disposed of later. Now you remove the
> > __init annotations from these probe functions. Wouldn't it be better to
> > convert the drivers to regular platform_driver_register instead?
> 
> Perhaps that paragraph was a bit unclear: I move them out of __init
> _and_ use platform_driver_register instead of platform_driver_probe as
> well.

Oh yes, I should have looked closer. Sorry for the noise.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |