* [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
@ 2025-08-17 7:55 Mohammad Gomaa
2025-08-19 16:09 ` Steven Rostedt
2025-09-04 20:04 ` Wolfram Sang
0 siblings, 2 replies; 7+ messages in thread
From: Mohammad Gomaa @ 2025-08-17 7:55 UTC (permalink / raw)
To: Wolfram Sang, Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers
Cc: linux-i2c, linux-kernel, linux-trace-kernel, kenalba, hbarnor,
rayxu, Mohammad Gomaa
Add tracepoints to i2c-core-base.c file to help trace
and debug I2C device probe failures.
The new trace points are:
- i2c_device_probe_debug: records non-failure routines
e.g. IRQ 0.
- i2c_device_probe_complete: records failed & successful
probbes with appropriate trace message.
To support operation of these tracepoints an enum
was added that stores log message for debug and failure.
Signed-off-by: Mohammad Gomaa <midomaxgomaa@gmail.com>
---
Hello,
This patch adds tracepoints to i2c-core-base to aid with debugging I2C probing failrues.
The motivation for this comes from my work in Google Summer of Code (GSoC) 2025:
"ChromeOS Platform Input Device Quality Monitoring"
https://summerofcode.withgoogle.com/programs/2025/projects/uCdIgK7K
This is my first submission to the Linux kernel, so any feedback is welcome.
---
Changes in v2:
- Refactored i2c_device_probe_failed to i2c_device_probe_complete
to support both successful and failed probes.
- Fixed formatting for TRACE_EVENT().
- Used enum instead of string variable for "reason".
- Link to v1: https://lore.kernel.org/r/20250806-refactor-add-i2c-tracepoints-v1-1-d1d39bd6fb57@gmail.com
---
drivers/i2c/i2c-core-base.c | 63 ++++++++++++++++++++++++--------
include/trace/events/i2c.h | 88 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 137 insertions(+), 14 deletions(-)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index ecca8c006b020379fb53293b20ab09ba25314609..7ca22759d26e85ee51bea60f414ed014e9bcec40 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -495,6 +495,8 @@ static int i2c_device_probe(struct device *dev)
struct i2c_driver *driver;
bool do_power_on;
int status;
+ int err_reason;
+ bool has_id_table, has_acpi_match, has_of_match;
if (!client)
return 0;
@@ -509,38 +511,54 @@ static int i2c_device_probe(struct device *dev)
/* Keep adapter active when Host Notify is required */
pm_runtime_get_sync(&client->adapter->dev);
irq = i2c_smbus_host_notify_to_irq(client);
+ err_reason = I2C_TRACE_REASON_HOST_NOTIFY;
} else if (is_of_node(fwnode)) {
irq = fwnode_irq_get_byname(fwnode, "irq");
if (irq == -EINVAL || irq == -ENODATA)
irq = fwnode_irq_get(fwnode, 0);
+ err_reason = I2C_TRACE_REASON_FROM_OF;
} else if (is_acpi_device_node(fwnode)) {
bool wake_capable;
irq = i2c_acpi_get_irq(client, &wake_capable);
if (irq > 0 && wake_capable)
client->flags |= I2C_CLIENT_WAKE;
+ err_reason = I2C_TRACE_REASON_FROM_ACPI;
}
if (irq == -EPROBE_DEFER) {
status = dev_err_probe(dev, irq, "can't get irq\n");
+ err_reason = I2C_TRACE_REASON_EPROBE_DEFER_IRQ;
goto put_sync_adapter;
}
- if (irq < 0)
+ if (irq < 0) {
+ trace_i2c_device_probe_debug(dev, err_reason);
irq = 0;
+ }
client->irq = irq;
}
driver = to_i2c_driver(dev->driver);
+ has_id_table = driver->id_table;
+ has_acpi_match = acpi_driver_match_device(dev, dev->driver);
+ has_of_match = i2c_of_match_device(dev->driver->of_match_table, client);
+
+ if (!has_id_table)
+ trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_NO_I2C_ID_TABLE);
+ if (!has_acpi_match)
+ trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_ACPI_ID_MISMATCH);
+ if (!has_of_match)
+ trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_OF_ID_MISMATCH);
+
/*
* An I2C ID table is not mandatory, if and only if, a suitable OF
* or ACPI ID table is supplied for the probing device.
*/
- if (!driver->id_table &&
- !acpi_driver_match_device(dev, dev->driver) &&
- !i2c_of_match_device(dev->driver->of_match_table, client)) {
+ if (!has_id_table && !has_acpi_match && !has_of_match) {
status = -ENODEV;
+ err_reason = I2C_TRACE_REASON_NO_ID_MATCH;
goto put_sync_adapter;
}
@@ -550,47 +568,60 @@ static int i2c_device_probe(struct device *dev)
wakeirq = fwnode_irq_get_byname(fwnode, "wakeup");
if (wakeirq == -EPROBE_DEFER) {
status = dev_err_probe(dev, wakeirq, "can't get wakeirq\n");
+ err_reason = I2C_TRACE_REASON_EPROBE_DEFER_WAKEIRQ;
goto put_sync_adapter;
}
device_init_wakeup(&client->dev, true);
- if (wakeirq > 0 && wakeirq != client->irq)
+ if (wakeirq > 0 && wakeirq != client->irq) {
status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
- else if (client->irq > 0)
+ err_reason = I2C_TRACE_REASON_SET_DED_WAKE_FAILED;
+ } else if (client->irq > 0) {
status = dev_pm_set_wake_irq(dev, client->irq);
- else
+ err_reason = I2C_TRACE_REASON_SET_WAKE_FAILED;
+ } else {
status = 0;
+ err_reason = I2C_TRACE_REASON_NO_IRQ;
+ }
- if (status)
+ if (status) {
dev_warn(&client->dev, "failed to set up wakeup irq\n");
+ trace_i2c_device_probe_debug(&client->dev, err_reason);
+ }
}
dev_dbg(dev, "probe\n");
status = of_clk_set_defaults(to_of_node(fwnode), false);
- if (status < 0)
+ if (status < 0) {
+ err_reason = I2C_TRACE_REASON_SET_DEF_CLOCKS;
goto err_clear_wakeup_irq;
-
+ }
do_power_on = !i2c_acpi_waive_d0_probe(dev);
status = dev_pm_domain_attach(&client->dev, do_power_on ? PD_FLAG_ATTACH_POWER_ON : 0);
- if (status)
+ if (status) {
+ err_reason = I2C_TRACE_REASON_ATTACH_PM_DOMAIN;
goto err_clear_wakeup_irq;
-
+ }
client->devres_group_id = devres_open_group(&client->dev, NULL,
GFP_KERNEL);
if (!client->devres_group_id) {
status = -ENOMEM;
+ err_reason = I2C_TRACE_REASON_OPEN_DEVRES_GROUP;
goto err_detach_pm_domain;
}
client->debugfs = debugfs_create_dir(dev_name(&client->dev),
client->adapter->debugfs);
- if (driver->probe)
+ if (driver->probe) {
status = driver->probe(client);
- else
+ err_reason = I2C_TRACE_REASON_PROBE_FAILED;
+ } else {
status = -EINVAL;
+ err_reason = I2C_TRACE_REASON_NO_PROBE;
+ }
/*
* Note that we are not closing the devres group opened above so
@@ -603,6 +634,8 @@ static int i2c_device_probe(struct device *dev)
if (status)
goto err_release_driver_resources;
+ trace_i2c_device_probe_complete(&client->dev, status, err_reason);
+
return 0;
err_release_driver_resources:
@@ -617,6 +650,8 @@ static int i2c_device_probe(struct device *dev)
if (client->flags & I2C_CLIENT_HOST_NOTIFY)
pm_runtime_put_sync(&client->adapter->dev);
+ trace_i2c_device_probe_complete(&client->dev, status, err_reason);
+
return status;
}
diff --git a/include/trace/events/i2c.h b/include/trace/events/i2c.h
index 142a23c6593c611de9abc2a89a146b95550b23cd..b00650ceba0a96a7cc538991ce5d5a45ea553715 100644
--- a/include/trace/events/i2c.h
+++ b/include/trace/events/i2c.h
@@ -16,6 +16,94 @@
/*
* drivers/i2c/i2c-core-base.c
*/
+#ifndef I2C_TRACE_REASON_ENUM_DEFINED
+#define I2C_TRACE_REASON_ENUM_DEFINED
+
+#define I2C_TRACE_REASON \
+EM(HOST_NOTIFY, "IRQ 0: could not get irq from Host Notify") \
+EM(FROM_OF, "IRQ 0: could not get irq from OF") \
+EM(FROM_ACPI, "IRQ 0: could not get irq from ACPI") \
+EM(EPROBE_DEFER_IRQ, "IRQ 0: could not get IRQ due to EPROBE_DEFER") \
+EM(NO_I2C_ID_TABLE, "no I2C ID table") \
+EM(ACPI_ID_MISMATCH, "ACPI ID table mismatch") \
+EM(OF_ID_MISMATCH, "OF ID table mismatch") \
+EM(NO_ID_MATCH, "no I2C ID table and no ACPI/OF match") \
+EM(EPROBE_DEFER_WAKEIRQ, "get wake IRQ due to EPROBE_DEFER") \
+EM(SET_DED_WAKE_FAILED, "failed to set dedicated wakeup IRQ") \
+EM(SET_WAKE_FAILED, "failed to set wakeup IRQ") \
+EM(NO_IRQ, "no IRQ") \
+EM(SET_DEF_CLOCKS, "set default clocks") \
+EM(ATTACH_PM_DOMAIN, "attach PM domain") \
+EM(OPEN_DEVRES_GROUP, "open devres group") \
+EM(PROBE_FAILED, "specific driver probe failed") \
+EMe(NO_PROBE, "no probe defined")
+
+#undef EM
+#undef EMe
+#define EM(a, b) I2C_TRACE_REASON_##a,
+#define EMe(a, b) I2C_TRACE_REASON_##a
+enum {
+ I2C_TRACE_REASON
+};
+
+#undef EM
+#undef EMe
+#define EM(a, b) TRACE_DEFINE_ENUM(I2C_TRACE_REASON_##a);
+#define EMe(a, b) TRACE_DEFINE_ENUM(I2C_TRACE_REASON_##a);
+I2C_TRACE_REASON
+
+#undef EM
+#undef EMe
+#define EM(a, b) { I2C_TRACE_REASON_##a, b },
+#define EMe(a, b) { I2C_TRACE_REASON_##a, b }
+
+#endif /* I2C_TRACE_REASON_ENUM_DEFINED */
+
+TRACE_EVENT(i2c_device_probe_debug,
+
+ TP_PROTO(struct device *dev, int err_reason),
+
+ TP_ARGS(dev, err_reason),
+
+ TP_STRUCT__entry(
+ __string( devname, dev_name(dev) )
+ __field( int, err_reason )
+ ),
+
+ TP_fast_assign(
+ __assign_str(devname);
+ __entry->err_reason = err_reason;
+ ),
+
+ TP_printk("device=%s: %s",
+ __get_str(devname),
+ __print_symbolic(__entry->err_reason, I2C_TRACE_REASON))
+);
+
+TRACE_EVENT(i2c_device_probe_complete,
+
+ TP_PROTO(struct device *dev, int status, int err_reason),
+
+ TP_ARGS(dev, status, err_reason),
+
+ TP_STRUCT__entry(
+ __string( dev_name, dev_name(dev) )
+ __field( int, status )
+ __field( int, err_reason )
+ ),
+
+ TP_fast_assign(
+ __assign_str(dev_name);
+ __entry->status = status;
+ __entry->err_reason = err_reason;
+ ),
+
+ TP_printk("%s probe %s: %s",
+ __get_str(dev_name),
+ __entry->status ? "failed" : "succeeded",
+ __entry->status ? __print_symbolic(__entry->err_reason, I2C_TRACE_REASON) : "")
+);
+
extern int i2c_transfer_trace_reg(void);
extern void i2c_transfer_trace_unreg(void);
---
base-commit: 7e161a991ea71e6ec526abc8f40c6852ebe3d946
change-id: 20250806-refactor-add-i2c-tracepoints-b6e2b92d4cd9
Best regards,
--
Mohammad Gomaa <midomaxgomaa@gmail.com>
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
2025-08-17 7:55 Mohammad Gomaa
@ 2025-08-18 7:19 ` Dan Carpenter
2025-09-04 20:04 ` Wolfram Sang
1 sibling, 0 replies; 7+ messages in thread
From: kernel test robot @ 2025-08-18 5:52 UTC (permalink / raw)
To: oe-kbuild; +Cc: lkp, Dan Carpenter
BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20250817-refactor-add-i2c-tracepoints-v2-1-c0bad299e02e@gmail.com>
References: <20250817-refactor-add-i2c-tracepoints-v2-1-c0bad299e02e@gmail.com>
TO: Mohammad Gomaa <midomaxgomaa@gmail.com>
TO: Wolfram Sang <wsa-dev@sang-engineering.com>
TO: Steven Rostedt <rostedt@goodmis.org>
TO: Masami Hiramatsu <mhiramat@kernel.org>
TO: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: linux-i2c@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-trace-kernel@vger.kernel.org
CC: kenalba@google.com
CC: hbarnor@chromium.org
CC: rayxu@google.com
CC: Mohammad Gomaa <midomaxgomaa@gmail.com>
Hi Mohammad,
kernel test robot noticed the following build warnings:
[auto build test WARNING on 7e161a991ea71e6ec526abc8f40c6852ebe3d946]
url: https://github.com/intel-lab-lkp/linux/commits/Mohammad-Gomaa/i2c-add-tracepoints-to-aid-debugging-in-i2c-core-base/20250817-155936
base: 7e161a991ea71e6ec526abc8f40c6852ebe3d946
patch link: https://lore.kernel.org/r/20250817-refactor-add-i2c-tracepoints-v2-1-c0bad299e02e%40gmail.com
patch subject: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
:::::: branch date: 24 hours ago
:::::: commit date: 24 hours ago
config: x86_64-randconfig-161-20250818 (https://download.01.org/0day-ci/archive/20250818/202508181525.GKAXMVYv-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202508181525.GKAXMVYv-lkp@intel.com/
smatch warnings:
drivers/i2c/i2c-core-base.c:535 i2c_device_probe() error: uninitialized symbol 'err_reason'.
vim +/err_reason +535 drivers/i2c/i2c-core-base.c
4d5538f5882a6b6 drivers/i2c/i2c-core.c Benjamin Tissoires 2016-10-13 490
f37dd80ac2a67e4 drivers/i2c/i2c-core.c David Brownell 2007-02-13 491 static int i2c_device_probe(struct device *dev)
^1da177e4c3f415 drivers/i2c/i2c-core.c Linus Torvalds 2005-04-16 492 {
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 493 struct fwnode_handle *fwnode = dev_fwnode(dev);
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 494 struct i2c_client *client = i2c_verify_client(dev);
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 495 struct i2c_driver *driver;
79ece9b292af6b0 drivers/i2c/i2c-core-base.c Ricardo Ribalda 2022-11-14 496 bool do_power_on;
50c3304a5e1e521 drivers/i2c/i2c-core.c Hans Verkuil 2008-03-12 497 int status;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 498 int err_reason;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 499 bool has_id_table, has_acpi_match, has_of_match;
7b4fbc50fabb810 drivers/i2c/i2c-core.c David Brownell 2007-05-01 500
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 501 if (!client)
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 502 return 0;
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 503
6e76cb7dfd34a2e drivers/i2c/i2c-core-base.c Charles Keepax 2019-06-27 504 client->irq = client->init_irq;
6e76cb7dfd34a2e drivers/i2c/i2c-core-base.c Charles Keepax 2019-06-27 505
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 506 if (!client->irq) {
845c877009cf014 drivers/i2c/i2c-core.c Mika Westerberg 2015-05-06 507 int irq = -ENOENT;
845c877009cf014 drivers/i2c/i2c-core.c Mika Westerberg 2015-05-06 508
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 509 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 510 dev_dbg(dev, "Using Host Notify IRQ\n");
72bfcee11cf8950 drivers/i2c/i2c-core-base.c Jarkko Nikula 2019-04-30 511 /* Keep adapter active when Host Notify is required */
72bfcee11cf8950 drivers/i2c/i2c-core-base.c Jarkko Nikula 2019-04-30 512 pm_runtime_get_sync(&client->adapter->dev);
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 513 irq = i2c_smbus_host_notify_to_irq(client);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 514 err_reason = I2C_TRACE_REASON_HOST_NOTIFY;
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 515 } else if (is_of_node(fwnode)) {
5d9424b00b577b6 drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 516 irq = fwnode_irq_get_byname(fwnode, "irq");
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 517 if (irq == -EINVAL || irq == -ENODATA)
5d9424b00b577b6 drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 518 irq = fwnode_irq_get(fwnode, 0);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 519 err_reason = I2C_TRACE_REASON_FROM_OF;
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 520 } else if (is_acpi_device_node(fwnode)) {
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 521 bool wake_capable;
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 522
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 523 irq = i2c_acpi_get_irq(client, &wake_capable);
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 524 if (irq > 0 && wake_capable)
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 525 client->flags |= I2C_CLIENT_WAKE;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 526 err_reason = I2C_TRACE_REASON_FROM_ACPI;
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 527 }
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 528 if (irq == -EPROBE_DEFER) {
5c52473b4496b35 drivers/i2c/i2c-core-base.c Xu Yang 2025-05-07 529 status = dev_err_probe(dev, irq, "can't get irq\n");
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 530 err_reason = I2C_TRACE_REASON_EPROBE_DEFER_IRQ;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 531 goto put_sync_adapter;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 532 }
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 533
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 534 if (irq < 0) {
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 @535 trace_i2c_device_probe_debug(dev, err_reason);
6f34be7400c68d3 drivers/i2c/i2c-core.c Geert Uytterhoeven 2014-11-17 536 irq = 0;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 537 }
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 538
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 539 client->irq = irq;
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 540 }
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 541
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 542 driver = to_i2c_driver(dev->driver);
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 543
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 544 has_id_table = driver->id_table;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 545 has_acpi_match = acpi_driver_match_device(dev, dev->driver);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 546 has_of_match = i2c_of_match_device(dev->driver->of_match_table, client);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 547
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 548 if (!has_id_table)
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 549 trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_NO_I2C_ID_TABLE);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 550 if (!has_acpi_match)
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 551 trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_ACPI_ID_MISMATCH);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 552 if (!has_of_match)
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 553 trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_OF_ID_MISMATCH);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 554
da10c06a044b375 drivers/i2c/i2c-core.c Lee Jones 2016-11-07 555 /*
f4b17a14faeec41 drivers/i2c/i2c-core-base.c Javier Martinez Canillas 2017-08-09 556 * An I2C ID table is not mandatory, if and only if, a suitable OF
f4b17a14faeec41 drivers/i2c/i2c-core-base.c Javier Martinez Canillas 2017-08-09 557 * or ACPI ID table is supplied for the probing device.
da10c06a044b375 drivers/i2c/i2c-core.c Lee Jones 2016-11-07 558 */
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 559 if (!has_id_table && !has_acpi_match && !has_of_match) {
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 560 status = -ENODEV;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 561 err_reason = I2C_TRACE_REASON_NO_ID_MATCH;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 562 goto put_sync_adapter;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 563 }
0acc2b321342aa8 drivers/i2c/i2c-core.c Lars-Peter Clausen 2013-09-29 564
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 565 if (client->flags & I2C_CLIENT_WAKE) {
3e99834cc0c7f06 drivers/i2c/i2c-core-base.c Andy Shevchenko 2019-07-26 566 int wakeirq;
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 567
5d9424b00b577b6 drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 568 wakeirq = fwnode_irq_get_byname(fwnode, "wakeup");
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 569 if (wakeirq == -EPROBE_DEFER) {
5c52473b4496b35 drivers/i2c/i2c-core-base.c Xu Yang 2025-05-07 570 status = dev_err_probe(dev, wakeirq, "can't get wakeirq\n");
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 571 err_reason = I2C_TRACE_REASON_EPROBE_DEFER_WAKEIRQ;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 572 goto put_sync_adapter;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 573 }
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 574
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 575 device_init_wakeup(&client->dev, true);
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 576
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 577 if (wakeirq > 0 && wakeirq != client->irq) {
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 578 status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 579 err_reason = I2C_TRACE_REASON_SET_DED_WAKE_FAILED;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 580 } else if (client->irq > 0) {
c18fba23061f16d drivers/i2c/i2c-core.c Grygorii Strashko 2015-11-12 581 status = dev_pm_set_wake_irq(dev, client->irq);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 582 err_reason = I2C_TRACE_REASON_SET_WAKE_FAILED;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 583 } else {
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 584 status = 0;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 585 err_reason = I2C_TRACE_REASON_NO_IRQ;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 586 }
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 587
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 588 if (status) {
b93d3d373924670 drivers/i2c/i2c-core.c Andy Shevchenko 2016-08-25 589 dev_warn(&client->dev, "failed to set up wakeup irq\n");
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 590 trace_i2c_device_probe_debug(&client->dev, err_reason);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 591 }
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 592 }
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 593
7b4fbc50fabb810 drivers/i2c/i2c-core.c David Brownell 2007-05-01 594 dev_dbg(dev, "probe\n");
d2653e92732bd39 drivers/i2c/i2c-core.c Jean Delvare 2008-04-29 595
3435b7f0fd28b9c drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 596 status = of_clk_set_defaults(to_of_node(fwnode), false);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 597 if (status < 0) {
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 598 err_reason = I2C_TRACE_REASON_SET_DEF_CLOCKS;
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 599 goto err_clear_wakeup_irq;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 600 }
79ece9b292af6b0 drivers/i2c/i2c-core-base.c Ricardo Ribalda 2022-11-14 601 do_power_on = !i2c_acpi_waive_d0_probe(dev);
d42c7c6fd66a6e2 drivers/i2c/i2c-core-base.c Claudiu Beznea 2025-07-03 602 status = dev_pm_domain_attach(&client->dev, do_power_on ? PD_FLAG_ATTACH_POWER_ON : 0);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 603 if (status) {
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 604 err_reason = I2C_TRACE_REASON_ATTACH_PM_DOMAIN;
74cedd30522819d drivers/i2c/i2c-core.c Kieran Bingham 2015-10-12 605 goto err_clear_wakeup_irq;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 606 }
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 607 client->devres_group_id = devres_open_group(&client->dev, NULL,
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 608 GFP_KERNEL);
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 609 if (!client->devres_group_id) {
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 610 status = -ENOMEM;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 611 err_reason = I2C_TRACE_REASON_OPEN_DEVRES_GROUP;
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 612 goto err_detach_pm_domain;
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 613 }
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 614
6250ebe666e425e drivers/i2c/i2c-core-base.c Guenter Roeck 2025-01-25 615 client->debugfs = debugfs_create_dir(dev_name(&client->dev),
6250ebe666e425e drivers/i2c/i2c-core-base.c Guenter Roeck 2025-01-25 616 client->adapter->debugfs);
6250ebe666e425e drivers/i2c/i2c-core-base.c Guenter Roeck 2025-01-25 617
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 618 if (driver->probe) {
03c835f498b5400 drivers/i2c/i2c-core-base.c Uwe Kleine-König 2023-02-26 619 status = driver->probe(client);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 620 err_reason = I2C_TRACE_REASON_PROBE_FAILED;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 621 } else {
b8a1a4cd5a98a2a drivers/i2c/i2c-core.c Lee Jones 2016-11-07 622 status = -EINVAL;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 623 err_reason = I2C_TRACE_REASON_NO_PROBE;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 624 }
b8a1a4cd5a98a2a drivers/i2c/i2c-core.c Lee Jones 2016-11-07 625
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 626 /*
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 627 * Note that we are not closing the devres group opened above so
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 628 * even resources that were attached to the device after probe is
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 629 * run are released when i2c_device_remove() is executed. This is
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 630 * needed as some drivers would allocate additional resources,
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 631 * for example when updating firmware.
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 632 */
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 633
72fa818e8a3145a drivers/i2c/i2c-core.c Wolfram Sang 2014-01-21 634 if (status)
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 635 goto err_release_driver_resources;
72fa818e8a3145a drivers/i2c/i2c-core.c Wolfram Sang 2014-01-21 636
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 637 trace_i2c_device_probe_complete(&client->dev, status, err_reason);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 638
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 639 return 0;
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 640
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 641 err_release_driver_resources:
6250ebe666e425e drivers/i2c/i2c-core-base.c Guenter Roeck 2025-01-25 642 debugfs_remove_recursive(client->debugfs);
5b5475826c5265c drivers/i2c/i2c-core-base.c Dmitry Torokhov 2021-03-21 643 devres_release_group(&client->dev, client->devres_group_id);
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 644 err_detach_pm_domain:
79ece9b292af6b0 drivers/i2c/i2c-core-base.c Ricardo Ribalda 2022-11-14 645 dev_pm_domain_detach(&client->dev, do_power_on);
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 646 err_clear_wakeup_irq:
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 647 dev_pm_clear_wake_irq(&client->dev);
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 648 device_init_wakeup(&client->dev, false);
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 649 put_sync_adapter:
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 650 if (client->flags & I2C_CLIENT_HOST_NOTIFY)
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 651 pm_runtime_put_sync(&client->adapter->dev);
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 652
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 653 trace_i2c_device_probe_complete(&client->dev, status, err_reason);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 654
50c3304a5e1e521 drivers/i2c/i2c-core.c Hans Verkuil 2008-03-12 655 return status;
f37dd80ac2a67e4 drivers/i2c/i2c-core.c David Brownell 2007-02-13 656 }
^1da177e4c3f415 drivers/i2c/i2c-core.c Linus Torvalds 2005-04-16 657
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
@ 2025-08-18 7:19 ` Dan Carpenter
0 siblings, 0 replies; 7+ messages in thread
From: Dan Carpenter @ 2025-08-18 7:19 UTC (permalink / raw)
To: oe-kbuild, Mohammad Gomaa, Wolfram Sang, Steven Rostedt,
Masami Hiramatsu, Mathieu Desnoyers
Cc: lkp, oe-kbuild-all, linux-i2c, linux-kernel, linux-trace-kernel,
kenalba, hbarnor, rayxu, Mohammad Gomaa
Hi Mohammad,
kernel test robot noticed the following build warnings:
url: https://github.com/intel-lab-lkp/linux/commits/Mohammad-Gomaa/i2c-add-tracepoints-to-aid-debugging-in-i2c-core-base/20250817-155936
base: 7e161a991ea71e6ec526abc8f40c6852ebe3d946
patch link: https://lore.kernel.org/r/20250817-refactor-add-i2c-tracepoints-v2-1-c0bad299e02e%40gmail.com
patch subject: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
config: x86_64-randconfig-161-20250818 (https://download.01.org/0day-ci/archive/20250818/202508181525.GKAXMVYv-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202508181525.GKAXMVYv-lkp@intel.com/
smatch warnings:
drivers/i2c/i2c-core-base.c:535 i2c_device_probe() error: uninitialized symbol 'err_reason'.
vim +/err_reason +535 drivers/i2c/i2c-core-base.c
f37dd80ac2a67e4 drivers/i2c/i2c-core.c David Brownell 2007-02-13 491 static int i2c_device_probe(struct device *dev)
^1da177e4c3f415 drivers/i2c/i2c-core.c Linus Torvalds 2005-04-16 492 {
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 493 struct fwnode_handle *fwnode = dev_fwnode(dev);
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 494 struct i2c_client *client = i2c_verify_client(dev);
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 495 struct i2c_driver *driver;
79ece9b292af6b0 drivers/i2c/i2c-core-base.c Ricardo Ribalda 2022-11-14 496 bool do_power_on;
50c3304a5e1e521 drivers/i2c/i2c-core.c Hans Verkuil 2008-03-12 497 int status;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 498 int err_reason;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 499 bool has_id_table, has_acpi_match, has_of_match;
7b4fbc50fabb810 drivers/i2c/i2c-core.c David Brownell 2007-05-01 500
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 501 if (!client)
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 502 return 0;
51298d1257b9f0a drivers/i2c/i2c-core.c Jean Delvare 2009-09-18 503
6e76cb7dfd34a2e drivers/i2c/i2c-core-base.c Charles Keepax 2019-06-27 504 client->irq = client->init_irq;
6e76cb7dfd34a2e drivers/i2c/i2c-core-base.c Charles Keepax 2019-06-27 505
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 506 if (!client->irq) {
845c877009cf014 drivers/i2c/i2c-core.c Mika Westerberg 2015-05-06 507 int irq = -ENOENT;
845c877009cf014 drivers/i2c/i2c-core.c Mika Westerberg 2015-05-06 508
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 509 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 510 dev_dbg(dev, "Using Host Notify IRQ\n");
72bfcee11cf8950 drivers/i2c/i2c-core-base.c Jarkko Nikula 2019-04-30 511 /* Keep adapter active when Host Notify is required */
72bfcee11cf8950 drivers/i2c/i2c-core-base.c Jarkko Nikula 2019-04-30 512 pm_runtime_get_sync(&client->adapter->dev);
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 513 irq = i2c_smbus_host_notify_to_irq(client);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 514 err_reason = I2C_TRACE_REASON_HOST_NOTIFY;
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 515 } else if (is_of_node(fwnode)) {
5d9424b00b577b6 drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 516 irq = fwnode_irq_get_byname(fwnode, "irq");
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 517 if (irq == -EINVAL || irq == -ENODATA)
5d9424b00b577b6 drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 518 irq = fwnode_irq_get(fwnode, 0);
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 519 err_reason = I2C_TRACE_REASON_FROM_OF;
5763a474c887d4a drivers/i2c/i2c-core-base.c Andy Shevchenko 2025-04-16 520 } else if (is_acpi_device_node(fwnode)) {
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 521 bool wake_capable;
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 522
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 523 irq = i2c_acpi_get_irq(client, &wake_capable);
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 524 if (irq > 0 && wake_capable)
b38f2d5d9615cf9 drivers/i2c/i2c-core-base.c Raul E Rangel 2022-09-29 525 client->flags |= I2C_CLIENT_WAKE;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 526 err_reason = I2C_TRACE_REASON_FROM_ACPI;
3fffd1283927342 drivers/i2c/i2c-core.c Dmitry Torokhov 2015-08-17 527 }
err_reason not set on else { path.
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 528 if (irq == -EPROBE_DEFER) {
5c52473b4496b35 drivers/i2c/i2c-core-base.c Xu Yang 2025-05-07 529 status = dev_err_probe(dev, irq, "can't get irq\n");
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 530 err_reason = I2C_TRACE_REASON_EPROBE_DEFER_IRQ;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 531 goto put_sync_adapter;
3c3dd56f760da05 drivers/i2c/i2c-core-base.c Alain Volmat 2020-04-30 532 }
331c34255293cd0 drivers/i2c/i2c-core.c Dmitry Torokhov 2017-01-04 533
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 534 if (irq < 0) {
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 @535 trace_i2c_device_probe_debug(dev, err_reason);
^^^^^^^^^^
6f34be7400c68d3 drivers/i2c/i2c-core.c Geert Uytterhoeven 2014-11-17 536 irq = 0;
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 537 }
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 538
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 539 client->irq = irq;
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 540 }
2fd36c55264926e drivers/i2c/i2c-core.c Laurent Pinchart 2014-10-30 541
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 542 driver = to_i2c_driver(dev->driver);
0c2a34937f7e4c4 drivers/i2c/i2c-core-base.c Wolfram Sang 2020-06-30 543
dc94c3bf033524a drivers/i2c/i2c-core-base.c Mohammad Gomaa 2025-08-17 544 has_id_table = driver->id_table;
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
2025-08-17 7:55 Mohammad Gomaa
@ 2025-08-19 16:09 ` Steven Rostedt
2025-09-04 20:04 ` Wolfram Sang
1 sibling, 0 replies; 7+ messages in thread
From: Steven Rostedt @ 2025-08-19 16:09 UTC (permalink / raw)
To: Mohammad Gomaa
Cc: Wolfram Sang, Masami Hiramatsu, Mathieu Desnoyers, linux-i2c,
linux-kernel, linux-trace-kernel, kenalba, hbarnor, rayxu
On Sun, 17 Aug 2025 10:55:14 +0300
Mohammad Gomaa <midomaxgomaa@gmail.com> wrote:
> Hello,
>
> This patch adds tracepoints to i2c-core-base to aid with debugging I2C probing failrues.
>
> The motivation for this comes from my work in Google Summer of Code (GSoC) 2025:
> "ChromeOS Platform Input Device Quality Monitoring"
> https://summerofcode.withgoogle.com/programs/2025/projects/uCdIgK7K
>
> This is my first submission to the Linux kernel, so any feedback is welcome.
Welcome Mohammad!
> driver = to_i2c_driver(dev->driver);
>
I'll let those that own this code discuss the merits of this, and if
there's a better way to achieve this. But I'll comment only on the tracing
aspect of this change.
> + has_id_table = driver->id_table;
> + has_acpi_match = acpi_driver_match_device(dev, dev->driver);
> + has_of_match = i2c_of_match_device(dev->driver->of_match_table, client);
> +
> + if (!has_id_table)
> + trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_NO_I2C_ID_TABLE);
> + if (!has_acpi_match)
> + trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_ACPI_ID_MISMATCH);
> + if (!has_of_match)
> + trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_OF_ID_MISMATCH);
The above adds if statements into the running code when tracing is disabled
and this causes pressure on the branch prediction and should be avoided. To
avoid this, you could use the trace_<tracepoint>_enabled() helper:
if (trace_i2c_device_probe_debug_enabled()) {
has_id_table = driver->id_table;
has_acpi_match = acpi_driver_match_device(dev, dev->driver);
has_of_match = i2c_of_match_device(dev->driver->of_match_table, client);
if (!has_id_table)
trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_NO_I2C_ID_TABLE);
if (!has_acpi_match)
trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_ACPI_ID_MISMATCH);
if (!has_of_match)
trace_i2c_device_probe_debug(dev, I2C_TRACE_REASON_OF_ID_MISMATCH);
}
But I suspect there's a better way to record this information. I just
wanted to inform you on the trace_<tracepoint>_enabled() logic. What it
does is to add a static branch (jump label) where there's no "if"
statement. It's either a nop that skips this code altogether, or it's a jmp
to the code that will do the logic as well as the tracing and then jump
back to where it left off.
It's much more efficient to use this and it doesn't add anything to the
branch prediction cache.
-- Steve
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
2025-08-17 7:55 Mohammad Gomaa
2025-08-19 16:09 ` Steven Rostedt
@ 2025-09-04 20:04 ` Wolfram Sang
2025-09-06 7:10 ` Mohammad Gomaa
1 sibling, 1 reply; 7+ messages in thread
From: Wolfram Sang @ 2025-09-04 20:04 UTC (permalink / raw)
To: Mohammad Gomaa
Cc: Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers, linux-i2c,
linux-kernel, linux-trace-kernel, kenalba, hbarnor, rayxu
[-- Attachment #1: Type: text/plain, Size: 1817 bytes --]
Hi Mohammad,
On Sun, Aug 17, 2025 at 10:55:14AM +0300, Mohammad Gomaa wrote:
> Add tracepoints to i2c-core-base.c file to help trace
> and debug I2C device probe failures.
>
> The new trace points are:
> - i2c_device_probe_debug: records non-failure routines
> e.g. IRQ 0.
> - i2c_device_probe_complete: records failed & successful
> probbes with appropriate trace message.
>
> To support operation of these tracepoints an enum
> was added that stores log message for debug and failure.
>
> Signed-off-by: Mohammad Gomaa <midomaxgomaa@gmail.com>
> ---
> Hello,
>
> This patch adds tracepoints to i2c-core-base to aid with debugging I2C probing failrues.
>
> The motivation for this comes from my work in Google Summer of Code (GSoC) 2025:
> "ChromeOS Platform Input Device Quality Monitoring"
> https://summerofcode.withgoogle.com/programs/2025/projects/uCdIgK7K
>
> This is my first submission to the Linux kernel, so any feedback is welcome.
Welcome to Kernel hacking!
I understand from the link above that this patch is intended for quality
assurance. With automatic testing, you can find regression of firmware
updates much easier.
The drawback is that it is quite some code for such a niche use case.
Also, I would think this code is very fragile because whenever the code
path in probe changes, one must ensure that err_reason is still set
accordingly. This adds maintenance burden.
I wonder if you can't use the output in the kernel log to identify
problems? We could add some if they are really missing. I know such
strings are not static. Still, my gut feeling says some application
should handle the complexity, not the kernel. Wouldn't we need a patch
like this for each and every subsystem if we follow that route?
Happy hacking,
Wolfram
[-- Attachment #2: signature.asc --]
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
2025-09-04 20:04 ` Wolfram Sang
@ 2025-09-06 7:10 ` Mohammad Gomaa
2025-09-06 8:08 ` Wolfram Sang
0 siblings, 1 reply; 7+ messages in thread
From: Mohammad Gomaa @ 2025-09-06 7:10 UTC (permalink / raw)
To: Wolfram Sang
Cc: Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers, linux-i2c,
linux-kernel, linux-trace-kernel, kenalba, hbarnor, rayxu
Hello everyone,
Thanks for your replies and guidance, I truly appreciate it.
ChromiumOS had a small subset of Chromebooks that had failing input devices
without any useful information in the Kernel logs, initially we
thought it had something
to do with the i2c probing logic, which led to us trying to improve
logging in the i2c probe function.
We started by adding a bunch of `dev_err` and `dev_debug` then we moved
to traces when we saw this Kernel Patch (note: it didn't get merged):
https://patchwork.kernel.org/project/linux-input/patch/C1C54D7FA3DF3958+20250710073148.3994900-1-wangyuli@uniontech.com/
My point is: we can always circle back to using `dev_err` and `dev_debug`,
while focusing on making the least amount of changes.
Few examples of where we think adding an extra log line would be beneficial:
- https://elixir.bootlin.com/linux/v6.6.94/source/drivers/i2c/i2c-core-base.c#L539-L544
(log that no driver were matched)
- https://elixir.bootlin.com/linux/v6.6.94/source/drivers/i2c/i2c-core-base.c#L614
(log that probing failed)
I hope this makes more sense, what do you think?
Thanks,
Mohammad Gomaa
On Thu, Sep 4, 2025 at 11:04 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
>
> Hi Mohammad,
>
> On Sun, Aug 17, 2025 at 10:55:14AM +0300, Mohammad Gomaa wrote:
> > Add tracepoints to i2c-core-base.c file to help trace
> > and debug I2C device probe failures.
> >
> > The new trace points are:
> > - i2c_device_probe_debug: records non-failure routines
> > e.g. IRQ 0.
> > - i2c_device_probe_complete: records failed & successful
> > probbes with appropriate trace message.
> >
> > To support operation of these tracepoints an enum
> > was added that stores log message for debug and failure.
> >
> > Signed-off-by: Mohammad Gomaa <midomaxgomaa@gmail.com>
> > ---
> > Hello,
> >
> > This patch adds tracepoints to i2c-core-base to aid with debugging I2C probing failrues.
> >
> > The motivation for this comes from my work in Google Summer of Code (GSoC) 2025:
> > "ChromeOS Platform Input Device Quality Monitoring"
> > https://summerofcode.withgoogle.com/programs/2025/projects/uCdIgK7K
> >
> > This is my first submission to the Linux kernel, so any feedback is welcome.
>
> Welcome to Kernel hacking!
>
> I understand from the link above that this patch is intended for quality
> assurance. With automatic testing, you can find regression of firmware
> updates much easier.
>
> The drawback is that it is quite some code for such a niche use case.
> Also, I would think this code is very fragile because whenever the code
> path in probe changes, one must ensure that err_reason is still set
> accordingly. This adds maintenance burden.
>
> I wonder if you can't use the output in the kernel log to identify
> problems? We could add some if they are really missing. I know such
> strings are not static. Still, my gut feeling says some application
> should handle the complexity, not the kernel. Wouldn't we need a patch
> like this for each and every subsystem if we follow that route?
>
> Happy hacking,
>
> Wolfram
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH WIP v2] i2c: add tracepoints to aid debugging in i2c-core-base
2025-09-06 7:10 ` Mohammad Gomaa
@ 2025-09-06 8:08 ` Wolfram Sang
0 siblings, 0 replies; 7+ messages in thread
From: Wolfram Sang @ 2025-09-06 8:08 UTC (permalink / raw)
To: Mohammad Gomaa
Cc: Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers, linux-i2c,
linux-kernel, linux-trace-kernel, kenalba, hbarnor, rayxu
[-- Attachment #1: Type: text/plain, Size: 1371 bytes --]
Hi Mohammad,
> We started by adding a bunch of `dev_err` and `dev_debug` then we moved
> to traces when we saw this Kernel Patch (note: it didn't get merged):
> https://patchwork.kernel.org/project/linux-input/patch/C1C54D7FA3DF3958+20250710073148.3994900-1-wangyuli@uniontech.com/
Tracepoints can make sense and we already have a few of them in the I2C
subsystem. Using them to propagate a new set of subsystem specific error
codes is not where tracepoints really shine IMHO.
> My point is: we can always circle back to using `dev_err` and `dev_debug`,
> while focusing on making the least amount of changes.
Good.
> Few examples of where we think adding an extra log line would be beneficial:
> - https://elixir.bootlin.com/linux/v6.6.94/source/drivers/i2c/i2c-core-base.c#L539-L544
> (log that no driver were matched)
If you enable debug printouts, it will be printed by the driver core.
Check the -ENODEV case of this function:
https://elixir.bootlin.com/linux/v6.6.94/source/drivers/base/dd.c#L572
At runtime, you can also check '/sys/bus/i2c/drivers/' if there are
symlinks to devices.
> - https://elixir.bootlin.com/linux/v6.6.94/source/drivers/i2c/i2c-core-base.c#L614
> (log that probing failed)
That really should be in the logs, because the same function as above
prints that with pr_warn (dev_err in recent kernels). No?
Happy hacking,
Wolfram
[-- Attachment #2: signature.asc --]
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^ permalink raw reply [flat|nested] 7+ messages in thread
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