diff mbox series

[RESEND,v5,2/5] driver core: add deferring probe reason to devices_deferred property

Message ID 20200624114127.3016-3-a.hajda@samsung.com (mailing list archive)
State New, archived
Headers show
Series driver core: add probe error check helper | expand

Commit Message

Andrzej Hajda June 24, 2020, 11:41 a.m. UTC
/sys/kernel/debug/devices_deferred property contains list of deferred devices.
This list does not contain reason why the driver deferred probe, the patch
improves it.
The natural place to set the reason is probe_err function introduced recently,
ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
will be attached to deferred device and printed when user read devices_deferred
property.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/base/base.h |  3 +++
 drivers/base/core.c | 10 ++++++----
 drivers/base/dd.c   | 21 ++++++++++++++++++++-
 3 files changed, 29 insertions(+), 5 deletions(-)

Comments

Rafael J. Wysocki June 24, 2020, 12:11 p.m. UTC | #1
On Wed, Jun 24, 2020 at 1:41 PM Andrzej Hajda <a.hajda@samsung.com> wrote:
>
> /sys/kernel/debug/devices_deferred property contains list of deferred devices.
> This list does not contain reason why the driver deferred probe, the patch
> improves it.
> The natural place to set the reason is probe_err function introduced recently,
> ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
> will be attached to deferred device and printed when user read devices_deferred
> property.
>
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> Reviewed-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> ---
>  drivers/base/base.h |  3 +++
>  drivers/base/core.c | 10 ++++++----
>  drivers/base/dd.c   | 21 ++++++++++++++++++++-
>  3 files changed, 29 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index 95c22c0f9036..93ef1c2f4c1f 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -93,6 +93,7 @@ struct device_private {
>         struct klist_node knode_class;
>         struct list_head deferred_probe;
>         struct device_driver *async_driver;
> +       char *deferred_probe_msg;

What about calling this deferred_probe_reason?

>         struct device *device;
>         u8 dead:1;
>  };
> @@ -134,6 +135,8 @@ extern void device_release_driver_internal(struct device *dev,
>  extern void driver_detach(struct device_driver *drv);
>  extern int driver_probe_device(struct device_driver *drv, struct device *dev);
>  extern void driver_deferred_probe_del(struct device *dev);
> +extern void __deferred_probe_set_msg(const struct device *dev,
> +                                    struct va_format *vaf);

I'd call this device_set_deferred_probe_reson() to follow the naming
convention for the function names in this header file.

>  static inline int driver_match_device(struct device_driver *drv,
>                                       struct device *dev)
>  {
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index ee9da66bff1b..2a96954d5460 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3962,6 +3962,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>   *
>   * This helper implements common pattern present in probe functions for error
>   * checking: print message if the error is not -EPROBE_DEFER and propagate it.
> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
> + * later by reading devices_deferred debugfs attribute.
>   * It replaces code sequence:
>   *     if (err != -EPROBE_DEFER)
>   *             dev_err(dev, ...);
> @@ -3977,14 +3979,14 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>         struct va_format vaf;
>         va_list args;
>
> -       if (err == -EPROBE_DEFER)
> -               return err;
> -
>         va_start(args, fmt);
>         vaf.fmt = fmt;
>         vaf.va = &args;
>
> -       dev_err(dev, "error %d: %pV", err, &vaf);
> +       if (err == -EPROBE_DEFER)
> +               __deferred_probe_set_msg(dev, &vaf);
> +       else
> +               dev_err(dev, "error %d: %pV", err, &vaf);
>
>         va_end(args);
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 9a1d940342ac..f44d26454b6a 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -27,6 +27,7 @@
>  #include <linux/async.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pinctrl/devinfo.h>
> +#include <linux/slab.h>
>
>  #include "base.h"
>  #include "power/power.h"
> @@ -136,6 +137,8 @@ void driver_deferred_probe_del(struct device *dev)
>         if (!list_empty(&dev->p->deferred_probe)) {
>                 dev_dbg(dev, "Removed from deferred list\n");
>                 list_del_init(&dev->p->deferred_probe);
> +               kfree(dev->p->deferred_probe_msg);
> +               dev->p->deferred_probe_msg = NULL;
>         }
>         mutex_unlock(&deferred_probe_mutex);
>  }
> @@ -211,6 +214,21 @@ void device_unblock_probing(void)
>         driver_deferred_probe_trigger();
>  }
>
> +/*
> + * __deferred_probe_set_msg() - Set defer probe reason message for device

I'd change this into a full kerneldoc comment.

> + */
> +void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
> +{
> +       const char *drv = dev_driver_string(dev);
> +
> +       mutex_lock(&deferred_probe_mutex);
> +
> +       kfree(dev->p->deferred_probe_msg);
> +       dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
> +
> +       mutex_unlock(&deferred_probe_mutex);
> +}
> +
>  /*
>   * deferred_devs_show() - Show the devices in the deferred probe pending list.
>   */
> @@ -221,7 +239,8 @@ static int deferred_devs_show(struct seq_file *s, void *data)
>         mutex_lock(&deferred_probe_mutex);
>
>         list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
> -               seq_printf(s, "%s\n", dev_name(curr->device));
> +               seq_printf(s, "%s\t%s", dev_name(curr->device),
> +                          curr->device->p->deferred_probe_msg ?: "\n");
>
>         mutex_unlock(&deferred_probe_mutex);
>
> --
> 2.17.1
>
Greg Kroah-Hartman June 24, 2020, 12:34 p.m. UTC | #2
On Wed, Jun 24, 2020 at 01:41:24PM +0200, Andrzej Hajda wrote:
> /sys/kernel/debug/devices_deferred property contains list of deferred devices.
> This list does not contain reason why the driver deferred probe, the patch
> improves it.
> The natural place to set the reason is probe_err function introduced recently,
> ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
> will be attached to deferred device and printed when user read devices_deferred
> property.
> 
> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> Reviewed-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> ---
>  drivers/base/base.h |  3 +++
>  drivers/base/core.c | 10 ++++++----
>  drivers/base/dd.c   | 21 ++++++++++++++++++++-
>  3 files changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index 95c22c0f9036..93ef1c2f4c1f 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -93,6 +93,7 @@ struct device_private {
>  	struct klist_node knode_class;
>  	struct list_head deferred_probe;
>  	struct device_driver *async_driver;
> +	char *deferred_probe_msg;
>  	struct device *device;
>  	u8 dead:1;
>  };
> @@ -134,6 +135,8 @@ extern void device_release_driver_internal(struct device *dev,
>  extern void driver_detach(struct device_driver *drv);
>  extern int driver_probe_device(struct device_driver *drv, struct device *dev);
>  extern void driver_deferred_probe_del(struct device *dev);
> +extern void __deferred_probe_set_msg(const struct device *dev,
> +				     struct va_format *vaf);
>  static inline int driver_match_device(struct device_driver *drv,
>  				      struct device *dev)
>  {
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index ee9da66bff1b..2a96954d5460 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3962,6 +3962,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>   *
>   * This helper implements common pattern present in probe functions for error
>   * checking: print message if the error is not -EPROBE_DEFER and propagate it.
> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
> + * later by reading devices_deferred debugfs attribute.
>   * It replaces code sequence:
>   * 	if (err != -EPROBE_DEFER)
>   * 		dev_err(dev, ...);
> @@ -3977,14 +3979,14 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>  	struct va_format vaf;
>  	va_list args;
>  
> -	if (err == -EPROBE_DEFER)
> -		return err;
> -
>  	va_start(args, fmt);
>  	vaf.fmt = fmt;
>  	vaf.va = &args;
>  
> -	dev_err(dev, "error %d: %pV", err, &vaf);
> +	if (err == -EPROBE_DEFER)
> +		__deferred_probe_set_msg(dev, &vaf);
> +	else
> +		dev_err(dev, "error %d: %pV", err, &vaf);
>  
>  	va_end(args);
>  
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 9a1d940342ac..f44d26454b6a 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -27,6 +27,7 @@
>  #include <linux/async.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/pinctrl/devinfo.h>
> +#include <linux/slab.h>
>  
>  #include "base.h"
>  #include "power/power.h"
> @@ -136,6 +137,8 @@ void driver_deferred_probe_del(struct device *dev)
>  	if (!list_empty(&dev->p->deferred_probe)) {
>  		dev_dbg(dev, "Removed from deferred list\n");
>  		list_del_init(&dev->p->deferred_probe);
> +		kfree(dev->p->deferred_probe_msg);
> +		dev->p->deferred_probe_msg = NULL;
>  	}
>  	mutex_unlock(&deferred_probe_mutex);
>  }
> @@ -211,6 +214,21 @@ void device_unblock_probing(void)
>  	driver_deferred_probe_trigger();
>  }
>  
> +/*
> + * __deferred_probe_set_msg() - Set defer probe reason message for device
> + */
> +void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
> +{
> +	const char *drv = dev_driver_string(dev);
> +
> +	mutex_lock(&deferred_probe_mutex);
> +
> +	kfree(dev->p->deferred_probe_msg);
> +	dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);

What about the device name?  Don't you also want that?

You want the same format that __dev_printk() outputs, please use that
to be consistant with all other messages that drivers are spitting out.

thanks,

greg k-h
Andrzej Hajda June 24, 2020, 1:26 p.m. UTC | #3
On 24.06.2020 14:34, Greg Kroah-Hartman wrote:
> On Wed, Jun 24, 2020 at 01:41:24PM +0200, Andrzej Hajda wrote:
>> /sys/kernel/debug/devices_deferred property contains list of deferred devices.
>> This list does not contain reason why the driver deferred probe, the patch
>> improves it.
>> The natural place to set the reason is probe_err function introduced recently,
>> ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
>> will be attached to deferred device and printed when user read devices_deferred
>> property.
>>
>> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
>> Reviewed-by: Mark Brown <broonie@kernel.org>
>> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
>> ---
>>   drivers/base/base.h |  3 +++
>>   drivers/base/core.c | 10 ++++++----
>>   drivers/base/dd.c   | 21 ++++++++++++++++++++-
>>   3 files changed, 29 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/base/base.h b/drivers/base/base.h
>> index 95c22c0f9036..93ef1c2f4c1f 100644
>> --- a/drivers/base/base.h
>> +++ b/drivers/base/base.h
>> @@ -93,6 +93,7 @@ struct device_private {
>>   	struct klist_node knode_class;
>>   	struct list_head deferred_probe;
>>   	struct device_driver *async_driver;
>> +	char *deferred_probe_msg;
>>   	struct device *device;
>>   	u8 dead:1;
>>   };
>> @@ -134,6 +135,8 @@ extern void device_release_driver_internal(struct device *dev,
>>   extern void driver_detach(struct device_driver *drv);
>>   extern int driver_probe_device(struct device_driver *drv, struct device *dev);
>>   extern void driver_deferred_probe_del(struct device *dev);
>> +extern void __deferred_probe_set_msg(const struct device *dev,
>> +				     struct va_format *vaf);
>>   static inline int driver_match_device(struct device_driver *drv,
>>   				      struct device *dev)
>>   {
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index ee9da66bff1b..2a96954d5460 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -3962,6 +3962,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>>    *
>>    * This helper implements common pattern present in probe functions for error
>>    * checking: print message if the error is not -EPROBE_DEFER and propagate it.
>> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
>> + * later by reading devices_deferred debugfs attribute.
>>    * It replaces code sequence:
>>    * 	if (err != -EPROBE_DEFER)
>>    * 		dev_err(dev, ...);
>> @@ -3977,14 +3979,14 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>>   	struct va_format vaf;
>>   	va_list args;
>>   
>> -	if (err == -EPROBE_DEFER)
>> -		return err;
>> -
>>   	va_start(args, fmt);
>>   	vaf.fmt = fmt;
>>   	vaf.va = &args;
>>   
>> -	dev_err(dev, "error %d: %pV", err, &vaf);
>> +	if (err == -EPROBE_DEFER)
>> +		__deferred_probe_set_msg(dev, &vaf);
>> +	else
>> +		dev_err(dev, "error %d: %pV", err, &vaf);
>>   
>>   	va_end(args);
>>   
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index 9a1d940342ac..f44d26454b6a 100644
>> --- a/drivers/base/dd.c
>> +++ b/drivers/base/dd.c
>> @@ -27,6 +27,7 @@
>>   #include <linux/async.h>
>>   #include <linux/pm_runtime.h>
>>   #include <linux/pinctrl/devinfo.h>
>> +#include <linux/slab.h>
>>   
>>   #include "base.h"
>>   #include "power/power.h"
>> @@ -136,6 +137,8 @@ void driver_deferred_probe_del(struct device *dev)
>>   	if (!list_empty(&dev->p->deferred_probe)) {
>>   		dev_dbg(dev, "Removed from deferred list\n");
>>   		list_del_init(&dev->p->deferred_probe);
>> +		kfree(dev->p->deferred_probe_msg);
>> +		dev->p->deferred_probe_msg = NULL;
>>   	}
>>   	mutex_unlock(&deferred_probe_mutex);
>>   }
>> @@ -211,6 +214,21 @@ void device_unblock_probing(void)
>>   	driver_deferred_probe_trigger();
>>   }
>>   
>> +/*
>> + * __deferred_probe_set_msg() - Set defer probe reason message for device
>> + */
>> +void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
>> +{
>> +	const char *drv = dev_driver_string(dev);
>> +
>> +	mutex_lock(&deferred_probe_mutex);
>> +
>> +	kfree(dev->p->deferred_probe_msg);
>> +	dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
> What about the device name?  Don't you also want that?


deferred_devs_show prints it already, deferred_probe_msg is appended if 
not null.


Regards

Andrzej


>
> You want the same format that __dev_printk() outputs, please use that
> to be consistant with all other messages that drivers are spitting out.
>
> thanks,
>
> greg k-h
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://protect2.fireeye.com/url?k=28daee95-7508f5cd-28db65da-0cc47a31c8b4-b3e8d1affcda9c08&q=1&u=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Fdri-devel
>
Andrzej Hajda June 24, 2020, 1:28 p.m. UTC | #4
On 24.06.2020 14:11, Rafael J. Wysocki wrote:
> On Wed, Jun 24, 2020 at 1:41 PM Andrzej Hajda <a.hajda@samsung.com> wrote:
>> /sys/kernel/debug/devices_deferred property contains list of deferred devices.
>> This list does not contain reason why the driver deferred probe, the patch
>> improves it.
>> The natural place to set the reason is probe_err function introduced recently,
>> ie. if probe_err will be called with -EPROBE_DEFER instead of printk the message
>> will be attached to deferred device and printed when user read devices_deferred
>> property.
>>
>> Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
>> Reviewed-by: Mark Brown <broonie@kernel.org>
>> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
>> ---
>>   drivers/base/base.h |  3 +++
>>   drivers/base/core.c | 10 ++++++----
>>   drivers/base/dd.c   | 21 ++++++++++++++++++++-
>>   3 files changed, 29 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/base/base.h b/drivers/base/base.h
>> index 95c22c0f9036..93ef1c2f4c1f 100644
>> --- a/drivers/base/base.h
>> +++ b/drivers/base/base.h
>> @@ -93,6 +93,7 @@ struct device_private {
>>          struct klist_node knode_class;
>>          struct list_head deferred_probe;
>>          struct device_driver *async_driver;
>> +       char *deferred_probe_msg;
> What about calling this deferred_probe_reason?
>
>>          struct device *device;
>>          u8 dead:1;
>>   };
>> @@ -134,6 +135,8 @@ extern void device_release_driver_internal(struct device *dev,
>>   extern void driver_detach(struct device_driver *drv);
>>   extern int driver_probe_device(struct device_driver *drv, struct device *dev);
>>   extern void driver_deferred_probe_del(struct device *dev);
>> +extern void __deferred_probe_set_msg(const struct device *dev,
>> +                                    struct va_format *vaf);
> I'd call this device_set_deferred_probe_reson() to follow the naming
> convention for the function names in this header file.
>
>>   static inline int driver_match_device(struct device_driver *drv,
>>                                        struct device *dev)
>>   {
>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>> index ee9da66bff1b..2a96954d5460 100644
>> --- a/drivers/base/core.c
>> +++ b/drivers/base/core.c
>> @@ -3962,6 +3962,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>>    *
>>    * This helper implements common pattern present in probe functions for error
>>    * checking: print message if the error is not -EPROBE_DEFER and propagate it.
>> + * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
>> + * later by reading devices_deferred debugfs attribute.
>>    * It replaces code sequence:
>>    *     if (err != -EPROBE_DEFER)
>>    *             dev_err(dev, ...);
>> @@ -3977,14 +3979,14 @@ int probe_err(const struct device *dev, int err, const char *fmt, ...)
>>          struct va_format vaf;
>>          va_list args;
>>
>> -       if (err == -EPROBE_DEFER)
>> -               return err;
>> -
>>          va_start(args, fmt);
>>          vaf.fmt = fmt;
>>          vaf.va = &args;
>>
>> -       dev_err(dev, "error %d: %pV", err, &vaf);
>> +       if (err == -EPROBE_DEFER)
>> +               __deferred_probe_set_msg(dev, &vaf);
>> +       else
>> +               dev_err(dev, "error %d: %pV", err, &vaf);
>>
>>          va_end(args);
>>
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index 9a1d940342ac..f44d26454b6a 100644
>> --- a/drivers/base/dd.c
>> +++ b/drivers/base/dd.c
>> @@ -27,6 +27,7 @@
>>   #include <linux/async.h>
>>   #include <linux/pm_runtime.h>
>>   #include <linux/pinctrl/devinfo.h>
>> +#include <linux/slab.h>
>>
>>   #include "base.h"
>>   #include "power/power.h"
>> @@ -136,6 +137,8 @@ void driver_deferred_probe_del(struct device *dev)
>>          if (!list_empty(&dev->p->deferred_probe)) {
>>                  dev_dbg(dev, "Removed from deferred list\n");
>>                  list_del_init(&dev->p->deferred_probe);
>> +               kfree(dev->p->deferred_probe_msg);
>> +               dev->p->deferred_probe_msg = NULL;
>>          }
>>          mutex_unlock(&deferred_probe_mutex);
>>   }
>> @@ -211,6 +214,21 @@ void device_unblock_probing(void)
>>          driver_deferred_probe_trigger();
>>   }
>>
>> +/*
>> + * __deferred_probe_set_msg() - Set defer probe reason message for device
> I'd change this into a full kerneldoc comment.


OK I will apply all changes in next version. Thx for review.


Regards

Andrzej


>
>> + */
>> +void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
>> +{
>> +       const char *drv = dev_driver_string(dev);
>> +
>> +       mutex_lock(&deferred_probe_mutex);
>> +
>> +       kfree(dev->p->deferred_probe_msg);
>> +       dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
>> +
>> +       mutex_unlock(&deferred_probe_mutex);
>> +}
>> +
>>   /*
>>    * deferred_devs_show() - Show the devices in the deferred probe pending list.
>>    */
>> @@ -221,7 +239,8 @@ static int deferred_devs_show(struct seq_file *s, void *data)
>>          mutex_lock(&deferred_probe_mutex);
>>
>>          list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
>> -               seq_printf(s, "%s\n", dev_name(curr->device));
>> +               seq_printf(s, "%s\t%s", dev_name(curr->device),
>> +                          curr->device->p->deferred_probe_msg ?: "\n");
>>
>>          mutex_unlock(&deferred_probe_mutex);
>>
>> --
>> 2.17.1
>>
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>
diff mbox series

Patch

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 95c22c0f9036..93ef1c2f4c1f 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -93,6 +93,7 @@  struct device_private {
 	struct klist_node knode_class;
 	struct list_head deferred_probe;
 	struct device_driver *async_driver;
+	char *deferred_probe_msg;
 	struct device *device;
 	u8 dead:1;
 };
@@ -134,6 +135,8 @@  extern void device_release_driver_internal(struct device *dev,
 extern void driver_detach(struct device_driver *drv);
 extern int driver_probe_device(struct device_driver *drv, struct device *dev);
 extern void driver_deferred_probe_del(struct device *dev);
+extern void __deferred_probe_set_msg(const struct device *dev,
+				     struct va_format *vaf);
 static inline int driver_match_device(struct device_driver *drv,
 				      struct device *dev)
 {
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ee9da66bff1b..2a96954d5460 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3962,6 +3962,8 @@  define_dev_printk_level(_dev_info, KERN_INFO);
  *
  * This helper implements common pattern present in probe functions for error
  * checking: print message if the error is not -EPROBE_DEFER and propagate it.
+ * In case of -EPROBE_DEFER it sets defer probe reason, which can be checked
+ * later by reading devices_deferred debugfs attribute.
  * It replaces code sequence:
  * 	if (err != -EPROBE_DEFER)
  * 		dev_err(dev, ...);
@@ -3977,14 +3979,14 @@  int probe_err(const struct device *dev, int err, const char *fmt, ...)
 	struct va_format vaf;
 	va_list args;
 
-	if (err == -EPROBE_DEFER)
-		return err;
-
 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
 
-	dev_err(dev, "error %d: %pV", err, &vaf);
+	if (err == -EPROBE_DEFER)
+		__deferred_probe_set_msg(dev, &vaf);
+	else
+		dev_err(dev, "error %d: %pV", err, &vaf);
 
 	va_end(args);
 
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9a1d940342ac..f44d26454b6a 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -27,6 +27,7 @@ 
 #include <linux/async.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/devinfo.h>
+#include <linux/slab.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -136,6 +137,8 @@  void driver_deferred_probe_del(struct device *dev)
 	if (!list_empty(&dev->p->deferred_probe)) {
 		dev_dbg(dev, "Removed from deferred list\n");
 		list_del_init(&dev->p->deferred_probe);
+		kfree(dev->p->deferred_probe_msg);
+		dev->p->deferred_probe_msg = NULL;
 	}
 	mutex_unlock(&deferred_probe_mutex);
 }
@@ -211,6 +214,21 @@  void device_unblock_probing(void)
 	driver_deferred_probe_trigger();
 }
 
+/*
+ * __deferred_probe_set_msg() - Set defer probe reason message for device
+ */
+void __deferred_probe_set_msg(const struct device *dev, struct va_format *vaf)
+{
+	const char *drv = dev_driver_string(dev);
+
+	mutex_lock(&deferred_probe_mutex);
+
+	kfree(dev->p->deferred_probe_msg);
+	dev->p->deferred_probe_msg = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
+
+	mutex_unlock(&deferred_probe_mutex);
+}
+
 /*
  * deferred_devs_show() - Show the devices in the deferred probe pending list.
  */
@@ -221,7 +239,8 @@  static int deferred_devs_show(struct seq_file *s, void *data)
 	mutex_lock(&deferred_probe_mutex);
 
 	list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
-		seq_printf(s, "%s\n", dev_name(curr->device));
+		seq_printf(s, "%s\t%s", dev_name(curr->device),
+			   curr->device->p->deferred_probe_msg ?: "\n");
 
 	mutex_unlock(&deferred_probe_mutex);