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Message-Id: <20230304005355.746421-2-saravanak@google.com>
Date: Fri, 3 Mar 2023 16:53:53 -0800
From: Saravana Kannan <saravanak@...gle.com>
To: Jonathan Corbet <corbet@....net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>
Cc: Saravana Kannan <saravanak@...gle.com>,
Abel Vesa <abel.vesa@...aro.org>,
Bjorn Andersson <andersson@...nel.org>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
Doug Anderson <dianders@...omium.org>,
Matthias Kaehlcke <mka@...omium.org>, kernel-team@...roid.com,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: [PATCH v2 1/2] driver core: Add fw_devlink.sync_state command line param
When all devices that could probe have finished probing (based on
deferred_probe_timeout configuration or late_initcall() when
!CONFIG_MODULES), this parameter controls what to do with devices that
haven't yet received their sync_state() calls.
fw_devlink.sync_state=strict is the default and the driver core will
continue waiting on all consumers of a device to probe successfully
before sync_state() is called for the device. This is the default
behavior since calling sync_state() on a device when all its consumers
haven't probed could make some systems unusable/unstable. When this
option is selected, we also print the list of devices that haven't had
sync_state() called on them by the time all devices the could probe have
finished probing.
fw_devlink.sync_state=timeout will cause the driver core to give up
waiting on consumers and call sync_state() on any devices that haven't
yet received their sync_state() calls. This option is provided for
systems that won't become unusable/unstable as they might be able to
save power (depends on state of hardware before kernel starts) if all
devices get their sync_state().
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
.../admin-guide/kernel-parameters.txt | 14 +++++
drivers/base/base.h | 1 +
drivers/base/core.c | 58 +++++++++++++++++++
drivers/base/dd.c | 6 ++
4 files changed, 79 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6221a1d057dd..fc5dc4dc9a5c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1582,6 +1582,20 @@
dependencies. This only applies for fw_devlink=on|rpm.
Format: <bool>
+ fw_devlink.sync_state =
+ [KNL] When all devices that could probe have finished
+ probing, this parameter controls what to do with
+ devices that haven't yet received their sync_state()
+ calls.
+ Format: { strict | timeout }
+ strict -- Default. Continue waiting on consumers to
+ probe successfully.
+ timeout -- Give up waiting on consumers and call
+ sync_state() on any devices that haven't yet
+ received their sync_state() calls after
+ deferred_probe_timeout has expired or by
+ late_initcall() if !CONFIG_MODULES.
+
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
diff --git a/drivers/base/base.h b/drivers/base/base.h
index 726a12a244c0..6fcd71803d35 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -209,6 +209,7 @@ extern void device_links_no_driver(struct device *dev);
extern bool device_links_busy(struct device *dev);
extern void device_links_unbind_consumers(struct device *dev);
extern void fw_devlink_drivers_done(void);
+extern void fw_devlink_probing_done(void);
/* device pm support */
void device_pm_move_to_tail(struct device *dev);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 6878dfcbf0d6..4c7e1550bb02 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1685,6 +1685,26 @@ static int __init fw_devlink_strict_setup(char *arg)
}
early_param("fw_devlink.strict", fw_devlink_strict_setup);
+#define FW_DEVLINK_SYNC_STATE_STRICT 0
+#define FW_DEVLINK_SYNC_STATE_TIMEOUT 1
+
+static int fw_devlink_sync_state;
+static int __init fw_devlink_sync_state_setup(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (strcmp(arg, "strict") == 0) {
+ fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_STRICT;
+ return 0;
+ } else if (strcmp(arg, "timeout") == 0) {
+ fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
+ return 0;
+ }
+ return -EINVAL;
+}
+early_param("fw_devlink.sync_state", fw_devlink_sync_state_setup);
+
static inline u32 fw_devlink_get_flags(u8 fwlink_flags)
{
if (fwlink_flags & FWLINK_FLAG_CYCLE)
@@ -1755,6 +1775,44 @@ void fw_devlink_drivers_done(void)
device_links_write_unlock();
}
+static int fw_devlink_dev_sync_state(struct device *dev, void *data)
+{
+ struct device_link *link = to_devlink(dev);
+ struct device *sup = link->supplier;
+
+ if (!(link->flags & DL_FLAG_MANAGED) ||
+ link->status == DL_STATE_ACTIVE || sup->state_synced ||
+ !dev_has_sync_state(sup))
+ return 0;
+
+ if (fw_devlink_sync_state == FW_DEVLINK_SYNC_STATE_STRICT) {
+ dev_warn(sup, "sync_state() pending due to %s\n",
+ dev_name(link->consumer));
+ return 0;
+ }
+
+ if (!list_empty(&sup->links.defer_sync))
+ return 0;
+
+ dev_warn(sup, "Timed out. Forcing sync_state()\n");
+ sup->state_synced = true;
+ get_device(sup);
+ list_add_tail(&sup->links.defer_sync, data);
+
+ return 0;
+}
+
+void fw_devlink_probing_done(void)
+{
+ LIST_HEAD(sync_list);
+
+ device_links_write_lock();
+ class_for_each_device(&devlink_class, NULL, &sync_list,
+ fw_devlink_dev_sync_state);
+ device_links_write_unlock();
+ device_links_flush_sync_list(&sync_list, NULL);
+}
+
/**
* wait_for_init_devices_probe - Try to probe any device needed for init
*
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 8def2ba08a82..84f07e0050dd 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -315,6 +315,8 @@ static void deferred_probe_timeout_work_func(struct work_struct *work)
list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
dev_info(p->device, "deferred probe pending\n");
mutex_unlock(&deferred_probe_mutex);
+
+ fw_devlink_probing_done();
}
static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
@@ -364,6 +366,10 @@ static int deferred_probe_initcall(void)
schedule_delayed_work(&deferred_probe_timeout_work,
driver_deferred_probe_timeout * HZ);
}
+
+ if (!IS_ENABLED(CONFIG_MODULES))
+ fw_devlink_probing_done();
+
return 0;
}
late_initcall(deferred_probe_initcall);
--
2.40.0.rc0.216.gc4246ad0f0-goog
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