On 30 July 2015 at 05:20, Rob Herring <robherring2@xxxxxxxxx> wrote:
> On Tue, Jul 28, 2015 at 8:19 AM, Tomeu Vizoso
> <tomeu.vizoso@xxxxxxxxxxxxx> wrote:
>> 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 <tomeu.vizoso@xxxxxxxxxxxxx>
>> ---
>>
>> 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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