Messages in this thread | | | Date | Wed, 9 Dec 2015 11:47:58 +0100 | From | Alexander Aring <> | Subject | Re: [PATCH v2 1/5] power: domain: add pm_genpd_exit |
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Hi,
On Tue, Dec 08, 2015 at 10:59:00AM -0800, Kevin Hilman wrote: > Jon Hunter <jonathanh@nvidia.com> writes: > > > On 04/12/15 17:45, Eric Anholt wrote: > >> From: Alexander Aring <alex.aring@gmail.com> > >> > >> This patch adds function pm_genpd_exit for undo a pm_genpd_init. This > >> is useful for multiple power domains while probing. If the probing fails > >> after one pm_genpd_init was called we need to undo all previous > >> registrations of generic pm domains inside the gpd_list list. > >> > >> There is a check on IS_ERR_OR_NULL(genpd) which is useful to check again > >> registered power domains and not registered domains, the driver can use > >> this mechanism to have an array with registered and non-registered power > >> domains, where non-registered power domains are NULL. > >> > >> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > >> Cc: Kevin Hilman <khilman@kernel.org> > >> Cc: Ulf Hansson <ulf.hansson@linaro.org> > >> Cc: Pavel Machek <pavel@ucw.cz> > >> Cc: Len Brown <len.brown@intel.com> > >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > >> Signed-off-by: Alexander Aring <alex.aring@gmail.com> > >> Signed-off-by: Eric Anholt <eric@anholt.net> > >> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> > >> --- > >> drivers/base/power/domain.c | 22 ++++++++++++++++++++++ > >> include/linux/pm_domain.h | 4 ++++ > >> 2 files changed, 26 insertions(+) > >> > >> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > >> index 167418e..e7aca27 100644 > >> --- a/drivers/base/power/domain.c > >> +++ b/drivers/base/power/domain.c > >> @@ -1509,6 +1509,28 @@ void pm_genpd_init(struct generic_pm_domain *genpd, > >> } > >> EXPORT_SYMBOL_GPL(pm_genpd_init); > >> > >> +/** > >> + * pm_genpd_exit - Uninitialize a generic I/O PM domain object. > >> + * @genpd: PM domain object to uninitialize. > >> + */ > >> +void pm_genpd_exit(struct generic_pm_domain *genpd) > >> +{ > >> + if (IS_ERR_OR_NULL(genpd)) > >> + return; > >> + > >> + /* check if domain is still in registered inside the pm subsystem */ > >> + WARN_ON_ONCE(!list_empty(&genpd->master_links) || > >> + !list_empty(&genpd->slave_links) || > >> + !list_empty(&genpd->dev_list)); > >> + > > > > Why not return an error here? Seems bad to remove it, if it could still > > be referenced by other domains. > > I had pointed this out as well in an earlier review. >
I talked with Ulf Hansson about such handling and there exists currently no handling to remove the pm_genpd on error handling (what our use case is for RPi domains).
The real solution would be a "pm_genpd_exit_recursive" functionality to remove subdomains, etc -> simple everything. Anway I am not a expert into power domain functionality and this simple approach was enough to him to add "something" which we have actually a lack of support.
Now "returning an errno" here:
I don't know how it should be handled in an "error handling" case. The WARN_ON_ONCE should say "somebody use this API wrong" which is a very unlikely case. These lists should be empty when calling pm_genpd_exit before in any case.
Example: the error case is while probing, how we react on a -EBUSY there "in an error case" -> simple ignore it? But then nobody see that the use of this function is wrong.
Should it be something like that?
err_probe: WARN_ON_ONCE(pm_genpd_exit(foo) < 0);
This function should be "void" here, I never saw some unregistration functionality which returns some "int" for error handling. Which brings us back to the "real" solution, a "pm_genpd_exit_recursive" functionality which unregister everything which belongs to a "generic_pm_domain".
To have a "pm_genpd_exit" is only the first step. That we can improve error handling for pm_genpd_init. (Which RPi power domains use and doesn't register any subdomains, etc. for probing).
> > Also not sure if you need to lock around the above test and removing the > > domain. > > > >> + mutex_lock(&gpd_list_lock); > >> + list_del(&genpd->gpd_list_node); > >> + mutex_unlock(&gpd_list_lock); > >> + > >> + mutex_destroy(&genpd->lock); > >> +} > >> +EXPORT_SYMBOL_GPL(pm_genpd_exit); > >> + > > > > BTW, I had just submitted a similar patch here [0]. So I would also like > > to see such an API added. >
:-)
> Between the two of you, maybe come up with an agreed upon patch and > re-submit. > > Kevin > > > Cheers > > Jon > > > > [0] http://marc.info/?l=devicetree&m=144924138932726&w=2
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