linux-kernel - Re: [PATCH 1/2] soc: ti: Use remoteproc auto

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Date:   Fri, 23 Dec 2016 11:05:58 -0600
From:   Suman Anna <s-anna@...com>
To:     Sarangdhar Joshi <spjoshi@...eaurora.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Santosh Shilimkar <ssantosh@...nel.org>
CC:     <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 12/15/2016 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.
> 
> No, may not be dropping this. Will try to handle it differently in
> rproc_del() (probably by making use of some state flag).
>>
>> 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.
> 
> Which scenario did it break? Booting up rproc device before
> wkup_m3_ipc_probe() causes issues?

Yes, our state machine requires the wkup_m3_ipc driver to control the
boot of the wkup_m3 remoteproc. The wkup_m3 is not a typical remoteproc,
it is our PM master and is responsible for putting the host processor
into suspend and waking it up in system suspend/cpuidle paths.
The remoteproc infrastructure is only used for load/boot, but the Linux
PM state machine and communication is all controlled by the wkup_m3_ipc
driver.

> 
> Nevertheless, I think Bjorn's suggestion of just dropping the call to
> wait_for_completion() and keeping kthread looks good, also because of
> the fact that rproc_boot() anyways calls request_firmware() and no
> longer needed to wait on asynchronous loading of firmware.

Yeah, I will have to test this, but looking at current code, this should
mostly be ok because of the remoteproc core changes w.r.t resource table
parsing.

regards
Suman