Messages in this thread | | | From | Saravana Kannan <> | Date | Wed, 24 Feb 2021 17:32:04 -0800 | Subject | Re: [PATCH] driver core: Avoid pointless deferred probe attempts |
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On Thu, Feb 18, 2021 at 9:24 AM Saravana Kannan <saravanak@google.com> wrote: > > On Thu, Feb 18, 2021 at 9:18 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > > > On Thu, Feb 18, 2021 at 12:51 AM Saravana Kannan <saravanak@google.com> wrote: > > > > > > 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. > > > > What if a matching driver module loads in the meantime? > > Driver registration always triggers a match attempt and this flag will > get set at that point. Yes, the user can disable autoprobe, but > that'll block deferred probes too. >
Let me know what you think Rafael.
-Saravana
> > > > > > > > > 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) > > > --
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