From: weili@codeaurora.org
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, vatsa@codeaurora.org
Subject: Re: [PATCH] driver-core: remove lock for platform devices during probe
Date: Mon, 24 Apr 2017 16:27:44 +0800 [thread overview]
Message-ID: <fb512df8405a4b6643e036af220ccc6c@codeaurora.org> (raw)
In-Reply-To: <20170424073232.GA19970@kroah.com>
Hi Greg,
We are optimizing boot time for Linux kernel and try to make some
platform drivers use asynchronous probe(by changing probe type of driver
to PROBE_PREFER_ASYNCHRONOUS) to reduce boot time. However we found the
platform drivers did not probe in parallel because they will lock the
same parent device(platform bus for platform drivers) during probe. So
we add this patch to remove lock of parent for platform device. This
will help to make platform driver probe in parallel and reduce boot
time.
Best Regards
Wei
On 2017-04-24 15:32, Greg Kroah-Hartman wrote:
> On Mon, Apr 24, 2017 at 01:42:16PM +0800, Wei Li wrote:
>> During driver probe procedure, lock on the parent of
>> platform devices could be removed to make probe in
>> parallel.
>>
>> Signed-off-by: Wei Li <weili@codeaurora.org>
>
> Why? Why does this matter?
>
>> ---
>> drivers/base/dd.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index a1fbf55..e238fbc 100644
>> --- a/drivers/base/dd.c
>> +++ b/drivers/base/dd.c
>> @@ -25,6 +25,7 @@
>> #include <linux/async.h>
>> #include <linux/pm_runtime.h>
>> #include <linux/pinctrl/devinfo.h>
>> +#include <linux/platform_device.h>
>>
>> #include "base.h"
>> #include "power/power.h"
>> @@ -749,13 +750,14 @@ static int __driver_attach(struct device *dev,
>> void *data)
>> return ret;
>> } /* ret > 0 means positive match */
>>
>> - if (dev->parent) /* Needed for USB */
>> + if (dev->parent &&
>> + (dev->bus != &platform_bus_type)) /* Needed for USB */
>
> The platform_bus_type check is not needed by USB, right?
>
> thanks,
>
> greg k-h
next prev parent reply other threads:[~2017-04-24 8:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-24 5:42 [PATCH] driver-core: remove lock for platform devices during probe Wei Li
2017-04-24 7:32 ` Greg Kroah-Hartman
2017-04-24 8:27 ` weili [this message]
2017-04-24 8:46 ` Greg Kroah-Hartman
2017-04-25 8:43 ` weili
2017-04-25 11:36 ` Greg Kroah-Hartman
2017-05-02 2:18 ` weili
2017-05-02 18:37 ` Greg Kroah-Hartman
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