On 30 July 2015 at 05:20, Rob Herring [off-list ref] wrote:

On Tue, Jul 28, 2015 at 8:19 AM, Tomeu Vizoso
[off-list ref] wrote:

quoted

Delay matches of platform devices until late_initcall, when we are sure
that all built-in drivers have been registered already.  This is needed
to prevent deferred probes because of some drivers not having registered
yet.

The reason why only platform devices are delayed is that some other
devices are expected to be probed earlier than late_initcall, for
example, the system PNP driver needs to probe its devices in
fs_initcall.

Signed-off-by: Tomeu Vizoso <redacted>
---

Changes in v2:
- Move delay to platform.c

 drivers/base/platform.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 063f0ab15259..fcf654678e27 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c

@@ -33,6 +33,8 @@
 /* For automatically allocated device IDs */
 static DEFINE_IDA(platform_devid_ida);

+static bool enable_matches;
+
 struct device platform_bus = {
        .init_name      = "platform",
 };

@@ -839,6 +841,15 @@ static int platform_match(struct device *dev, struct device_driver *drv)
        struct platform_device *pdev = to_platform_device(dev);
        struct platform_driver *pdrv = to_platform_driver(drv);

+       /*
+        * Delay matches of platform devices until late_initcall, when we are
+        * sure that all built-in drivers have been registered already. This
+        * is needed to prevent deferred probes because of some drivers
+        * not having registered yet.
+        */
+       if (!enable_matches)
+               return false;
+

Having this as a global makes me nervous. I think it would be better
to be DT specific or per device some how. Perhaps use OF_POPULATED_BUS
flag as an additional test.

I see no problem with restricting this to platform devices with an
of_node (or a fwnode if we still want to address machines with ACPI).

There could be non-DT platforms that rely on the initcall ordering and
moving all probes to late_initcall could change the ordering. I'm not
sure though.

Yeah, I'm not sure how much that could be a problem. Maybe if a
non-platform device has a match and probes before a platform device
that has been delayed and is a dependency of it. That could be a
problem in platforms that don't do on-demand probing because of the
lack of firmware data.

Thanks,

Tomeu

Rob
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