linux-kernel - Re: [PATCH 1/2] PM / Domains: Add GENPD_FLAG_SUSPEND

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Date:   Wed, 12 Aug 2020 21:42:59 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Kevin Hilman <khilman@...libre.com>
Cc:     bjorn.andersson@...aro.org, ulf.hansson@...aro.org,
        rjw@...ysocki.net, agross@...nel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        gregkh@...uxfoundation.org, pavel@....cz, len.brown@...el.com,
        rnayak@...eaurora.org, dianders@...omium.org, khilman@...nel.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH 1/2] PM / Domains: Add GENPD_FLAG_SUSPEND_ON flag

Kevin,
Thanks for taking time to review the
series!

On 2020-08-12 05:49, Kevin Hilman wrote:
> Sibi Sankar <sibis@...eaurora.org> writes:
> 
>> This is for power domains which needs to stay powered on for suspend
>> but can be powered on/off as part of runtime PM. This flag is aimed at
>> power domains coupled to remote processors which enter suspend states
>> independent to that of the application processor. Such power domains
>> are turned off only on remote processor crash/shutdown.
>> 
>> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> 
> Seems like a useful use-case, but i think there should be a bit more
> description/documentation about what is the expected/desired behavior
> during system suspsend when a power-domain with this flag is already
> runtime-PM suspended.  Similarily, on system resume, what is the
> expected/desired behavior?

SUSPEND_ON flag is only aimed at
keeping power domains powered on
across suspend (only if its already
powered on). Also if the power domain
is runtime-PM suspended we wouldn't
want to power it on during resume.

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 0a5afca250d03..547c091618008 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1003,7 +1003,7 @@ static void genpd_sync_power_on(struct 
generic_pm_domain *genpd, bool use_lock,
  {
         struct gpd_link *link;

-       if (genpd_status_on(genpd))
+       if (genpd_status_on(genpd) || genpd_is_suspend_on(genpd))
                 return;

I'll add the ^^ diff in the next
re-spin to prevent power on of
a runtime-PM suspended power
domain.

> 
> Kevin

-- 
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