From: Ajay Agarwal <ajayagarwal@google.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>, Pavel Machek <pavel@ucw.cz>,
Len Brown <len.brown@intel.com>,
Leonard Crestez <leonard.crestez@nxp.com>
Cc: linux-pm@vger.kernel.org, manugautam@google.com,
mshavit@google.com, quangh@google.com, vamshigajjela@google.com
Subject: Lets not expect domains marked as `RPM_ALWAYS_ON`/`ALWAYS_ON` to be ON at boot
Date: Fri, 1 Dec 2023 11:35:57 +0530 [thread overview]
Message-ID: <ZWl3xd7lc5pnnIcz@google.com> (raw)
Hello Linux PM experts
For a given power domain, if the `genpd->flags` has the GENPD_FLAG_RPM_ALWAYS_ON
flag set, then pm_genpd_init expects that domain to be ON:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/base/power/domain.c?h=v6.7-rc3#n2102
I have a usecase where the power domain is not ON by default on kernel boot,
but I also want it to stay ON during RPM. But the current logic fails the
`pm_genpd_init` for me.
IMO, the kernel should not force a PD which needs to stay ON during RPM to be ON
at boot also. It is quite possible that the PD will be turned ON for the very
first time by a client driver in the kernel itself.
Additionally, I think the kernel as well should not enforce this for PDs which
do not want to turn OFF ever, i.e., the ones which have `GENPD_FLAG_ALWAYS_ON`
flag set. Let the kernel turn ON these PDs when it wants and only then prevent
the RPM or system suspend from turning these domains OFF.
Proposed patch in pm_genpd_init:
```
- /* Always-on domains must be powered on at initialization. */
- if ((genpd_is_always_on(genpd) || genpd_is_rpm_always_on(genpd)) &&
- !genpd_status_on(genpd)) {
- pr_err("always-on PM domain %s is not on\n", genpd->name);
- return -EINVAL;
- }
-
```
Looking for your views here.
Thanks
Ajay
next reply other threads:[~2023-12-01 6:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-01 6:05 Ajay Agarwal [this message]
2023-12-01 12:12 ` Lets not expect domains marked as `RPM_ALWAYS_ON`/`ALWAYS_ON` to be ON at boot Ulf Hansson
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