From mboxrd@z Thu Jan 1 00:00:00 1970 From: f.fainelli@gmail.com (Florian Fainelli) Date: Sun, 16 Jul 2017 08:35:59 -0700 Subject: [RFC 1/2] PM / suspend: Add platform_suspend_target_state() In-Reply-To: <20170716134116.wxwb3gevbhlereij@piout.net> References: <20170622085102.mpk7vxodpgxtrlfd@piout.net> <2497538.J9F6XFeBfd@aspire.rjw.lan> <20170715062838.GA20741@amd> <5864280.u6UQBsuXnA@aspire.rjw.lan> <20170715164626.GA1373@amd> <1a5ef0ae-16f3-5a61-ae4e-083664cb30c0@gmail.com> <20170715183358.4bnhshokalyulswz@piout.net> <20170706031819.GD12954@xo-6d-61-c0.localdomain> <20170716134116.wxwb3gevbhlereij@piout.net> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/16/2017 06:41 AM, Alexandre Belloni wrote: > On 06/07/2017 at 05:18:19 +0200, Pavel Machek wrote: >> On Sat 2017-07-15 20:33:58, Alexandre Belloni wrote: >>> On 15/07/2017 at 10:20:27 -0700, Florian Fainelli wrote: >>>>> We already have >>>>> >>>>> struct regulator_state { >>>>> int uV; /* suspend voltage */ >>>>> unsigned int mode; /* suspend regulator operating mode */ >>>>> int enabled; /* is regulator enabled in this suspend state */ >>>>> int disabled; /* is the regulator disabled in this suspend state */ >>>>> }; >>>>> >>>>> * struct regulation_constraints - regulator operating constraints. >>>>> * @state_disk: State for regulator when system is suspended in disk >>>>> * mode. >>>>> * @state_mem: State for regulator when system is suspended in mem >>>>> * mode. >>>>> * @state_standby: State for regulator when system is suspended in >>>>> * standby >>>>> * mode. >>>>> >>>>> . So it seems that maybe we should tell the drivers if we are entering >>>>> "state_mem" or "state_standby" (something I may have opposed, sorry), >>>>> then the driver can get neccessary information from regulator >>>>> framework. >>>> >>>> OK, so what would be the mechanism to tell these drivers about the >>>> system wide suspend state they are entering if it is not via >>>> platform_suspend_target_state()? >>>> >>>> Keep in mind that regulators might be one aspect of what could be >>>> causing the platform to behave specifically in one suspend state vs. >>>> another, but there could be pieces of HW within the SoC that can't be >>>> described with power domains, voltage islands etc. that would still have >>>> inherent suspend states properties (like memory retention, pin/pad >>>> controls etc. etc). We still need some mechanism, possibly centralized >>>> >>> >>> I concur, the regulator stuff is one aspect of one of our suspend state >>> (cutting VDDcore). But we have another state where the main clock (going >>> to the IPs) is going from a few hundred MHz to 32kHz. This is currently >>> handled by calling at91_suspend_entering_slow_clock(). I think it is >>> important to take that into account so we can remove this hack from the >>> kernel. >> >> Cure should not be worse then the disease... and it is in this case. >> >> For clocks, take a look at clock framework, perhaps it already has "clock_will_be_suspended" >> as regulator framework had. If not, implement it. >> > > See Rafael's comment, currently, the clock framework can't say whether > the clock will change because it doesn't know anything about the suspend > target. > >> Same with memory retention, pin/pad controls. >> > > Same here. Exactly, here is another side effect of not knowing the platform suspend/state that I came across on our platforms: https://patchwork.kernel.org/patch/9561575/ (we later discussed this in details with Linus and this is why this very patch set is being introduced now) -- Florian