The v4l2-async module operations are quite complex to follow, due to the
asynchronous nature of subdevices and notifiers registration and
matching procedures. In order to help with debugging of failed or
erroneous matching between a subdevice and the notifier collected
async_subdevice it gets matched against, introduce a few dev_dbg() calls
in v4l2_async core operations.
Protect the debug operations with a Kconfig defined symbol, to make sure
when debugging is disabled, no additional code or data is added to the
module.
Notifiers are identified by the name of the subdevice or v4l2_dev they are
registered by, while subdevice matching which now happens on endpoints,
need a longer description built walking the fwnode graph backwards
collecting parent nodes names (otherwise we would have had printouts
like: "Matching "endpoint" with "endpoint"" which are not that useful).
Signed-off-by: Jacopo Mondi <jacopo+rene...@jmondi.org>
---
For fwnodes backed by OF, I may have used the "%pOF" format modifier to
get the full node name instead of parsing the fwnode graph by myself with
"v4l2_async_fwnode_full_name()". Unfortunately I'm not aware of anything
like "%pOF" for ACPI backed fwnodes. Also, walking the fwnode graph by
myself allows me to reduce the depth, to reduce the debug messages output
length which is anyway long enough to result disturbing on a 80columns
terminal window.
---
drivers/media/v4l2-core/Kconfig | 8 ++++
drivers/media/v4l2-core/v4l2-async.c | 81 ++++++++++++++++++++++++++++++++++++
2 files changed, 89 insertions(+)
diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index a35c336..8331736 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -17,6 +17,14 @@ config VIDEO_ADV_DEBUG
V4L devices.
In doubt, say N.
+config VIDEO_V4L2_ASYNC_DEBUG
+ bool "Enable debug functionalities for V4L2 async module"
+ depends on VIDEO_V4L2
+ default n
+ ---help---
+ Say Y here to enable debug output in V4L2 async module.
+ In doubt, say N.
+
config VIDEO_FIXED_MINOR_RANGES
bool "Enable old-style fixed minor ranges on drivers/video devices"
default n
diff --git a/drivers/media/v4l2-core/v4l2-async.c
b/drivers/media/v4l2-core/v4l2-async.c
index c13a781..307e1a5 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -8,6 +8,10 @@
* published by the Free Software Foundation.
*/
+#if defined(CONFIG_VIDEO_V4L2_ASYNC_DEBUG)
+#define DEBUG
+#endif
+
#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
@@ -25,6 +29,52 @@
#include <media/v4l2-fwnode.h>
#include <media/v4l2-subdev.h>
+#if defined(CONFIG_VIDEO_V4L2_ASYNC_DEBUG)
+#define V4L2_ASYNC_FWNODE_NAME_LEN 512
+
+static void __v4l2_async_fwnode_full_name(char *name,
+ unsigned int len,
+ unsigned int max_depth,
+ struct fwnode_handle *fwnode)
+{
+ unsigned int buf_len = len < V4L2_ASYNC_FWNODE_NAME_LEN ?
+ len : V4L2_ASYNC_FWNODE_NAME_LEN;
+ char __tmp[V4L2_ASYNC_FWNODE_NAME_LEN];
+ struct fwnode_handle *parent;
+
+ memset(name, 0, buf_len);
+ buf_len -= snprintf(__tmp, buf_len, "%s", fwnode_get_name(fwnode));
+
+ parent = fwnode;
+ while ((parent = fwnode_get_parent(parent)) && buf_len &&
+ --max_depth) {
+ buf_len -= snprintf(name, buf_len, "%s/%s",
+ fwnode_get_name(parent), __tmp);
+ strcpy(__tmp, name);
+ }
+}
+
+static void v4l2_async_fwnode_full_name(char *name,
+ unsigned int len,
+ struct fwnode_handle *fwnode)
+{
+ /*
+ * Usually 4 as nesting level is sufficient to identify an
+ * endpoint firmware node uniquely.
+ */
+ __v4l2_async_fwnode_full_name(name, len, 4, fwnode);
+}
+
+#else /* CONFIG_VIDEO_V4L2_ASYNC_DEBUG */
+#define V4L2_ASYNC_FWNODE_NAME_LEN 0
+
+static void v4l2_async_fwnode_full_name(char *name,
+ unsigned int len,
+ struct fwnode_handle *fwnode)
+{
+}
+#endif /* CONFIG_VIDEO_V4L2_ASYNC_DEBUG */
+
static struct device *v4l2_async_notifier_dev(
struct v4l2_async_notifier *notifier)
{
@@ -54,9 +104,12 @@ static void v4l2_async_notifier_call_unbind(struct
v4l2_async_notifier *n,
static int v4l2_async_notifier_call_complete(struct v4l2_async_notifier *n)
{
+ struct device *dev = v4l2_async_notifier_dev(n);
if (!n->ops || !n->ops->complete)
return 0;
+ dev_dbg(dev, "Complete notifier \"%s\"\n", fwnode_get_name(n->owner));
+
return n->ops->complete(n);
}
@@ -100,8 +153,17 @@ static struct v4l2_async_subdev *v4l2_async_find_match(
struct v4l2_async_notifier *notifier, struct v4l2_subdev *sd)
{
bool (*match)(struct v4l2_subdev *, struct v4l2_async_subdev *);
+ struct device *dev = v4l2_async_notifier_dev(notifier);
+ char asd_full_name[V4L2_ASYNC_FWNODE_NAME_LEN];
+ char sd_full_name[V4L2_ASYNC_FWNODE_NAME_LEN];
struct v4l2_async_subdev *asd;
+ v4l2_async_fwnode_full_name(sd_full_name, V4L2_ASYNC_FWNODE_NAME_LEN,
+ sd->fwnode);
+
+ dev_dbg(dev, "Match notifier \"%s\" with subdevice \"%s\"\n",
+ fwnode_get_name(notifier->owner), sd_full_name);
+
list_for_each_entry(asd, ¬ifier->waiting, list) {
/* bus_type has been verified valid before */
switch (asd->match_type) {
@@ -115,6 +177,11 @@ static struct v4l2_async_subdev *v4l2_async_find_match(
match = match_i2c;
break;
case V4L2_ASYNC_MATCH_FWNODE:
+ v4l2_async_fwnode_full_name(asd_full_name,
+ V4L2_ASYNC_FWNODE_NAME_LEN,
+ asd->match.fwnode.fwnode);
+ dev_dbg(dev, "Test sd \"%s\" with async_sd \"%s\"\n",
+ sd_full_name, asd_full_name);
match = match_fwnode;
break;
default:
@@ -198,9 +265,16 @@ static int v4l2_async_match_notify(struct
v4l2_async_notifier *notifier,
struct v4l2_subdev *sd,
struct v4l2_async_subdev *asd)
{
+ struct device *dev = v4l2_async_notifier_dev(notifier);
struct v4l2_async_notifier *subdev_notifier;
+ char sd_full_name[V4L2_ASYNC_FWNODE_NAME_LEN];
int ret;
+ v4l2_async_fwnode_full_name(sd_full_name, V4L2_ASYNC_FWNODE_NAME_LEN,
+ sd->fwnode);
+ dev_dbg(dev, "Matched sd: \"%s\" with notifier \"%s\"\n",
+ sd_full_name, fwnode_get_name(notifier->owner));
+
ret = v4l2_device_register_subdev(v4l2_dev, sd);
if (ret < 0)
return ret;
@@ -240,6 +314,7 @@ static int v4l2_async_match_notify(struct
v4l2_async_notifier *notifier,
static int v4l2_async_notifier_try_all_subdevs(
struct v4l2_async_notifier *notifier)
{
+ struct device *dev = v4l2_async_notifier_dev(notifier);
struct v4l2_device *v4l2_dev =
v4l2_async_notifier_find_v4l2_dev(notifier);
struct v4l2_subdev *sd;
@@ -247,6 +322,9 @@ static int v4l2_async_notifier_try_all_subdevs(
if (!v4l2_dev)
return 0;
+ dev_dbg(dev, "Testing notifier \"%s\" against all subdevices\n",
+ fwnode_get_name(notifier->owner));
+
again:
list_for_each_entry(sd, &subdev_list, async_list) {
struct v4l2_async_subdev *asd;
@@ -378,6 +456,9 @@ static int __v4l2_async_notifier_register(struct
v4l2_async_notifier *notifier)
notifier->owner = dev_fwnode(dev);
+ dev_dbg(dev, "Registering notifier \"%s\"\n",
+ fwnode_get_name(notifier->owner));
+
mutex_lock(&list_lock);
for (i = 0; i < notifier->num_subdevs; i++) {
--
2.7.4
