From: rishabhb@codeaurora.org
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ckadabi@codeaurora.org, tsoni@codeaurora.org,
Vikram Mulukutla <markivx@codeaurora.org>,
rjwysocki@gmail.com
Subject: Re: [PATCH] dd: Invoke one probe retry cycle after every initcall level
Date: Mon, 23 Jul 2018 13:22:50 -0700 [thread overview]
Message-ID: <e4ca8572ed913ab65f63be8a351d4439@codeaurora.org> (raw)
In-Reply-To: <CAJZ5v0gWqx5Op-Bbg7bAYALCyBPsc=-+homAYj2Q1qd3WsqmDw@mail.gmail.com>
On 2018-07-23 04:17, Rafael J. Wysocki wrote:
> On Thu, Jul 19, 2018 at 11:24 PM, Rishabh Bhatnagar
> <rishabhb@codeaurora.org> wrote:
>> Drivers that are registered at an initcall level may have to
>> wait until late_init before the probe deferral mechanism can
>> retry their probe functions. It is possible that their
>> dependencies were resolved much earlier, in some cases even
>> before the next initcall level. Invoke one probe retry cycle
>> at every _sync initcall level, allowing these drivers to be
>> probed earlier.
>
> Can you please say something about the actual use case this is
> expected to address?
We have a display driver that depends 3 other devices to be
probed so that it can bring-up the display. Because of dependencies
not being met the deferral mechanism defers the probes for a later time,
even though the dependencies might be met earlier. With this change
display can be brought up much earlier.
>
>> Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
>> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
>> ---
>> drivers/base/dd.c | 33 +++++++++++++++++++++++++++------
>> 1 file changed, 27 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> index 1435d72..e6a6821 100644
>> --- a/drivers/base/dd.c
>> +++ b/drivers/base/dd.c
>> @@ -224,23 +224,44 @@ void device_unblock_probing(void)
>> driver_deferred_probe_trigger();
>> }
>>
>> +static void enable_trigger_defer_cycle(void)
>> +{
>> + driver_deferred_probe_enable = true;
>> + driver_deferred_probe_trigger();
>> + /*
>> + * Sort as many dependencies as possible before the next
>> initcall
>> + * level
>> + */
>> + flush_work(&deferred_probe_work);
>> +}
>> +
>> /**
>> * deferred_probe_initcall() - Enable probing of deferred devices
>> *
>> * We don't want to get in the way when the bulk of drivers are
>> getting probed.
>> * Instead, this initcall makes sure that deferred probing is delayed
>> until
>> - * late_initcall time.
>> + * all the registered initcall functions at a particular level are
>> completed.
>> + * This function is invoked at every *_initcall_sync level.
>> */
>> static int deferred_probe_initcall(void)
>> {
>> - driver_deferred_probe_enable = true;
>> - driver_deferred_probe_trigger();
>> - /* Sort as many dependencies as possible before exiting
>> initcalls */
>> - flush_work(&deferred_probe_work);
>> + enable_trigger_defer_cycle();
>> + driver_deferred_probe_enable = false;
>> + return 0;
>> +}
>> +arch_initcall_sync(deferred_probe_initcall);
>> +subsys_initcall_sync(deferred_probe_initcall);
>> +fs_initcall_sync(deferred_probe_initcall);
>> +device_initcall_sync(deferred_probe_initcall);
>> +
>> +static int deferred_probe_enable_fn(void)
>> +{
>> + /* Enable deferred probing for all time */
>> + enable_trigger_defer_cycle();
>> initcalls_done = true;
>> return 0;
>> }
>> -late_initcall(deferred_probe_initcall);
>> +late_initcall(deferred_probe_enable_fn);
>>
>> /**
>> * device_is_bound() - Check if device is bound to a driver
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>> Forum,
>> a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2018-07-23 20:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-19 21:24 [PATCH] dd: Invoke one probe retry cycle after every initcall level Rishabh Bhatnagar
2018-07-23 11:17 ` Rafael J. Wysocki
2018-07-23 20:22 ` rishabhb [this message]
2018-07-24 8:24 ` Rafael J. Wysocki
2018-08-01 21:18 ` rishabhb
2018-08-01 21:21 ` Rafael J. Wysocki
[not found] ` <CA+tyz+6ZwtpKM=G5F2Do_sXWyo8r83ma19fWpn4HELiy0XT7=w@mail.gmail.com>
2018-08-02 22:20 ` Sodagudi Prasad
2018-08-06 8:53 ` Rafael J. Wysocki
2018-08-09 22:30 ` rishabhb
2018-08-10 7:10 ` Rafael J. Wysocki
2018-08-10 17:19 ` Sodagudi Prasad
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