On 20 December 2017 at 10:02, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: > Hi Ulf, > > On Wednesday 20 December 2017 02:05 PM, Ulf Hansson wrote: >> On 20 December 2017 at 07:42, Kishon Vijay Abraham I <kishon@xxxxxx> wrote: >>> Hi Ulf, >>> >>> On Wednesday 20 December 2017 02:52 AM, Ulf Hansson wrote: >>>> The runtime PM deployment in the phy core is a bit unnecessary complicated >>>> and the main reason is because it operates on the phy device, which is >>>> created by the phy core and assigned as a child device of the phy provider >>>> device. >>>> >>>> Let's simplify the code, by replacing the existing calls to >>>> phy_pm_runtime_get_sync() and phy_pm_runtime_put(), with regular calls to >>>> pm_runtime_get_sync() and pm_runtime_put(). While doing that, let's also >>>> change to give the phy provider device as the parameter to the runtime PM >>>> calls. This together with adding error paths, that allows the phy >>>> provider device to be runtime PM disabled, enables further clean up the >>>> code. More precisely, we can simply avoid to enable runtime PM for the phy >>>> device altogether, so let's do that as well. >>>> >>>> More importantly, this change also fixes an issue for system suspend. >>>> Especially in those cases when the phy provider device gets put into a low >>>> power state via calling the pm_runtime_force_suspend() helper, as is the >>>> case for a Renesas SoC, which has the phy provider device attached to the >>>> generic PM domain. >>>> >>>> The problem in this case, is that pm_runtime_force_suspend() expects the >>>> child device of the provider device to be runtime suspended, else this will >>>> trigger a WARN splat (correctly) when runtime PM gets re-enabled at system >>>> resume. >>>> >>>> In the current case, even if phy_power_off() triggers a pm_runtime_put() >>>> during system suspend the phy device (child) doesn't get runtime suspended, >>>> because that is prevented in the system suspend phases. However, by >>>> avoiding to enable runtime PM, this problem goes away. >>>> >>>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> >>>> --- >>>> drivers/phy/phy-core.c | 33 +++++++++++++-------------------- >>>> 1 file changed, 13 insertions(+), 20 deletions(-) >>>> >>>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c >>>> index b4964b0..9fa3f13 100644 >>>> --- a/drivers/phy/phy-core.c >>>> +++ b/drivers/phy/phy-core.c >>>> @@ -222,10 +222,10 @@ int phy_init(struct phy *phy) >>>> if (!phy) >>>> return 0; >>>> >>>> - ret = phy_pm_runtime_get_sync(phy); >>>> - if (ret < 0 && ret != -ENOTSUPP) >>>> + ret = pm_runtime_get_sync(phy->dev.parent); >>> >>> Won't this make phy-core manage pm_runtime of phy_provider even though the >>> phy_provider might not intend it? >> >> No it shouldn't. >> >> There are two cases to consider around this. >> >> 1) CONFIG_PM is unset. In this case pm_runtime_get_sync() will return >> 1, which is treated as succeeds by the error path. >> >> 2) CONFIG_PM is set, but the phy provider don't use runtime PM, thus >> it hasn't called pm_runtime_enable() for its device. In this case, >> pm_runtime_get_sync() returns -EACCES, which is also treated as >> success by the error path. > > There can be a case where the phy_provider uses runtime PM but doesn't want > phy-core to manage it. Ah, so you mean there are cases when the provider driver calls pm_runtime_enable() *after* it calls phy_create()/dev_phy_create() instead of before? I am not really sure I understand *why* a provider driver wants to do that though, do you have more details? I mean, even if the phy core handles runtime PM, additional management can be done on top in the phy provider, there is nothing preventing that, but I guess that isn't sufficient? Kind regards Uffe
