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Subject[PATCH] driver core: Avoid pointless deferred probe attempts
From
There's no point in adding a device to the deferred probe list if we
know for sure that it doesn't have a matching driver. So, check if a
device can match with a driver before adding it to the deferred probe
list.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
Geert,

Can you give this a shot for your I2C DMA issue with fw_devlink=on?

-Saravana

drivers/base/dd.c | 6 ++++++
include/linux/device.h | 4 ++++
2 files changed, 10 insertions(+)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9179825ff646..f18963f42e21 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -123,6 +123,9 @@ static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);

void driver_deferred_probe_add(struct device *dev)
{
+ if (!dev->can_match)
+ return;
+
mutex_lock(&deferred_probe_mutex);
if (list_empty(&dev->p->deferred_probe)) {
dev_dbg(dev, "Added to deferred list\n");
@@ -726,6 +729,7 @@ static int driver_probe_device(struct device_driver *drv, struct device *dev)
if (!device_is_registered(dev))
return -ENODEV;

+ dev->can_match = true;
pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);

@@ -829,6 +833,7 @@ static int __device_attach_driver(struct device_driver *drv, void *_data)
return 0;
} else if (ret == -EPROBE_DEFER) {
dev_dbg(dev, "Device match requests probe deferral\n");
+ dev->can_match = true;
driver_deferred_probe_add(dev);
} else if (ret < 0) {
dev_dbg(dev, "Bus failed to match device: %d\n", ret);
@@ -1064,6 +1069,7 @@ static int __driver_attach(struct device *dev, void *data)
return 0;
} else if (ret == -EPROBE_DEFER) {
dev_dbg(dev, "Device match requests probe deferral\n");
+ dev->can_match = true;
driver_deferred_probe_add(dev);
} else if (ret < 0) {
dev_dbg(dev, "Bus failed to match device: %d\n", ret);
diff --git a/include/linux/device.h b/include/linux/device.h
index 7619a84f8ce4..1f9cc1ba78bc 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -438,6 +438,9 @@ struct dev_links_info {
* @state_synced: The hardware state of this device has been synced to match
* the software state of this device by calling the driver/bus
* sync_state() callback.
+ * @can_match: The device has matched with a driver at least once or it is in
+ * a bus (like AMBA) which can't check for matching drivers until
+ * other devices probe successfully.
* @dma_coherent: this particular device is dma coherent, even if the
* architecture supports non-coherent devices.
* @dma_ops_bypass: If set to %true then the dma_ops are bypassed for the
@@ -544,6 +547,7 @@ struct device {
bool offline:1;
bool of_node_reused:1;
bool state_synced:1;
+ bool can_match:1;
#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
--
2.30.0.478.g8a0d178c01-goog
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