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Date:   Fri, 23 Dec 2016 10:55:35 -0600
From:   Suman Anna <s-anna@...com>
To:     Sarangdhar Joshi <spjoshi@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     Ohad Ben-Cohen <ohad@...ery.com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arm-msm@...r.kernel.org>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Trilok Soni <tsoni@...eaurora.org>,
        Dave Gerlach <d-gerlach@...com>
Subject: Re: [PATCH 1/2] soc: ti: Use remoteproc auto_boot feature

Hi Sarang,

On 12/22/2016 06:07 PM, Sarangdhar Joshi wrote:
> On 12/22/2016 5:02 AM, Bjorn Andersson wrote:
>> On Wed 21 Dec 19:16 PST 2016, Suman Anna wrote:
>>
>>> Hi Sarang,
>>>
>>> On 12/15/2016 06:03 PM, Sarangdhar Joshi wrote:
>>>> The function wkup_m3_rproc_boot_thread waits for asynchronous
>>>> firmware loading to complete successfully before calling
>>>> rproc_boot(). The same can be achieved by just setting
>>>> rproc->auto_boot flag. Change this. As a result this change
>>>> removes wkup_m3_rproc_boot_thread and moves m3_ipc->sync_complete
>>>> initialization to the wkup_m3_ipc_probe().
>>>>
>>>> Other than the current usage, the firmware_loading_complete is
>>>> only used in rproc_del() where it's no longer needed.  This
>>>> change is in preparation for removing firmware_loading_complete
>>>> completely.
>>>
>>> Based on the comments so far, I am assuming that you are dropping this
>>> series.
>>>
>>
>> Following up on those comments only revealed that we have several other
>> similar race conditions, so I'm hoping that Sarangdhar will continue to
>> work on fixing those - and in this process get rid of this completion.
>>
>>> In any case, this series did break our PM stack. We definitely don't
>>> want to auto-boot the wkup_m3_rproc device, that responsibility will
>>> need to stay with the wkup_m3_ipc driver.
>>>
>>
>> Reviewing the wkup_m3 situation again I see that as we have moved the
>> resource table parsing to the rproc_boot() path there's no longer any
>> need for the wkup_m3_ipc driver to wait for the remoteproc-core-internal
>> completion.
>>
>> If rproc_get_by_phandle() returns non-NULL it is initialized. We still
>> don't want to call rproc_boot() from wkup_m3_ipc_probe(), so let's keep
>> the wkup_m3_rproc_boot_thread().
> 
> Did you mean it's okay to call rproc_boot() from wkup_m3_ipc_probe()?
> rproc_boot() calls request_firmware() anyways and so there is no need to
> wait for completion of asynchronous firmware loading.

No, please retain the kthread. I think you miss the purpose of this wait
for completion originally. Before all the core changes in 4.9, the
resource table is parsed in the first asynchronous loading step, and we
had to wait for that step to complete. Now that there's no table parsing
during the request_firmware_no_wait() for non auto-boot, we can get away
from the need for a synchronzition call.

> 
>>
>> Sarangdhar, could you update the wkup_m3_ipc patch to just drop the
>> wait_for_completion() call?
> 
> Sure, assuming we should still keep the rproc_boot() call in the kthread.

Yep.

regards
Suman

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