Re: [PATCH 02/13] driver-core: defer all probes until late_initcall

Rafael J. Wysocki
2015-06-18T21:24:15Z

On Wednesday, June 17, 2015 03:42:12 PM Tomeu Vizoso wrote:
> To decrease the chances of devices deferring their probes because of
> dependencies not having probed yet because of their drivers not having
> registered yet, delay all probing until the late initcall level.
>
> This will allow us to avoid deferred probes completely later by probing
> dependencies on demand, or by probing them in dependency order.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> ---
> drivers/base/dd.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index a638bbb..18438aa 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -407,6 +407,12 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
> if (!device_is_registered(dev))
> return -ENODEV;
>
> + /* Defer all probes until we start processing the queue */
> + if (!driver_deferred_probe_enable) {
> + driver_deferred_probe_add(dev);

Do I think correctly that this will effectively force everybody to use deferred
probing?

> + return 0;
> + }
> +
> pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
> drv->bus->name, __func__, dev_name(dev), drv->name);
>
> @@ -585,7 +591,7 @@ EXPORT_SYMBOL_GPL(device_attach);
>
> void device_initial_probe(struct device *dev)
> {
> - __device_attach(dev, true);
> + __device_attach(dev, driver_deferred_probe_enable);
> }
>
> static int __driver_attach(struct device *dev, void *data)
>

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.