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From: Andrzej Hajda <a.hajda@samsung.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jernej Skrabec <jernej.skrabec@siol.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Jonas Karlman <jonas@kwiboo.se>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	linux-kernel@vger.kernel.org,
	"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	andy.shevchenko@gmail.com, Mark Brown <broonie@kernel.org>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	linux-arm-kernel@lists.infradead.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: [PATCH v6 2/4] driver core: add deferring probe reason to devices_deferred property
Date: Fri, 26 Jun 2020 12:01:01 +0200
Message-ID: <20200626100103.18879-3-a.hajda@samsung.com> (raw)
In-Reply-To: <20200626100103.18879-1-a.hajda@samsung.com>

/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 |  8 ++++++--
 drivers/base/dd.c   | 23 ++++++++++++++++++++++-
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 95c22c0f9036..6954fccab3d7 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_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 device_set_deferred_probe_reson(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 3a827c82933f..fee047f03681 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -3963,6 +3963,8 @@ define_dev_printk_level(_dev_info, KERN_INFO);
  * This helper implements common pattern present in probe functions for error
  * checking: print debug or error message depending if the error value is
  * -EPROBE_DEFER and propagate error upwards.
+ * In case of -EPROBE_DEFER it sets also 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, ...);
@@ -3984,10 +3986,12 @@ int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
 	vaf.fmt = fmt;
 	vaf.va = &args;
 
-	if (err != -EPROBE_DEFER)
+	if (err != -EPROBE_DEFER) {
 		dev_err(dev, "error %d: %pV", err, &vaf);
-	else
+	} else {
+		device_set_deferred_probe_reson(dev, &vaf);
 		dev_dbg(dev, "error %d: %pV", err, &vaf);
+	}
 
 	va_end(args);
 
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9a1d940342ac..dd5683b61f74 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_reason);
+		dev->p->deferred_probe_reason = NULL;
 	}
 	mutex_unlock(&deferred_probe_mutex);
 }
@@ -211,6 +214,23 @@ void device_unblock_probing(void)
 	driver_deferred_probe_trigger();
 }
 
+/**
+ * device_set_deferred_probe_reson() - Set defer probe reason message for device
+ * @dev: the pointer to the struct device
+ * @vaf: the pointer to va_format structure with message
+ */
+void device_set_deferred_probe_reson(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_reason);
+	dev->p->deferred_probe_reason = 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 +241,8 @@ 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_reason ?: "\n");
 
 	mutex_unlock(&deferred_probe_mutex);
 
-- 
2.17.1


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  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200626100108eucas1p2c6d68625f3755a467d7316dd27704f7c@eucas1p2.samsung.com>
2020-06-26 10:00 ` [PATCH v6 0/4] driver core: add probe error check helper Andrzej Hajda
     [not found]   ` <CGME20200626100109eucas1p25331652d017cd17d21c0ae60541d1f73@eucas1p2.samsung.com>
2020-06-26 10:01     ` [PATCH v6 1/4] driver core: add device probe log helper Andrzej Hajda
2020-06-26 15:41       ` Rafael J. Wysocki
2020-06-26 16:22       ` Sam Ravnborg
2020-07-01  9:29       ` Grygorii Strashko
     [not found]   ` <CGME20200626100110eucas1p2c5b91f2c98a5c6e5739f5af3207d192e@eucas1p2.samsung.com>
2020-06-26 10:01     ` Andrzej Hajda [this message]
2020-06-26 15:43       ` [PATCH v6 2/4] driver core: add deferring probe reason to devices_deferred property Rafael J. Wysocki
2020-06-26 17:11       ` Grygorii Strashko
2020-06-29 11:28         ` Andrzej Hajda
2020-06-30  8:59           ` Grygorii Strashko
2020-06-30 15:41             ` Andrzej Hajda
2020-06-30 18:00               ` Dmitry Torokhov
2020-07-02  6:57                 ` Andrzej Hajda
2020-07-07  4:14                   ` Dmitry Torokhov
2020-07-10  7:42                     ` Andrzej Hajda
2020-07-10 11:07                       ` Mark Brown
     [not found]   ` <CGME20200626100110eucas1p24327c924dada0c2e86ecf0ab5b5af571@eucas1p2.samsung.com>
2020-06-26 10:01     ` [PATCH v6 3/4] drm/bridge/sii8620: fix resource acquisition error handling Andrzej Hajda
2020-06-29  8:33       ` Neil Armstrong
     [not found]   ` <CGME20200626100111eucas1p18e175e6c77af483bd80fb90c171b05db@eucas1p1.samsung.com>
2020-06-26 10:01     ` [PATCH v6 4/4] drm/bridge: lvds-codec: simplify " Andrzej Hajda
2020-06-29  8:33       ` Neil Armstrong

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