On Fri, Mar 31, 2017 at 02:28:11PM +0200, Lucas Stach wrote: > Hi Dong, > > Am Samstag, den 01.04.2017, 12:10 +0800 schrieb Dong Aisheng: > [...] > > > If we need the domains to be up before the consumers, the only > > > way to deal with that is to select CONFIG_PM and > > > CONFIG_PM_GENERIC_DOMAINS from the platform, so we have proper probe > > > defer handling for consumer devices of the power domains. > > > > > > > A bit confuse about these words... > > If those options are selected we get proper PROBE_DEFER handling for > consumers of the power domain, so probe order doesn't matter. > > > > > Personally i'd be more like Rockchip's power domain implementation. > > > > > > Why? > > > > > > > See: > > > > arch/arm/boot/dts/rk3288.dtsi > > > > drivers/soc/rockchip/pm_domains.c > > > > Dcumentation/devicetree/bindings/soc/rockchip/power_domain.txt > > > > > > > > How about refer to the Rockchip's way? > > > > > > Why? We just changed the way how it's done for GPCv1, after more than 1 > > > year of those patches being on the list. Why should we do it differently > > > for GPCv2? > > > > > > > Hmm? > > > > I just thought your GPCv1 change was picked a few weeks ago (Feb 17 2017) > > and there's no current users in kernel of the new binding. > > That's why i come out of the idea if we could improve it before any users. > > > > Maybe i made mistake? > > The patches to change this have been out for over 1 year. I'm less than > motivated to change the binding again, after it has gone through the DT > review and has finally been picked up. > > > See: > > commit 721cabf6c6600dbe689ee2782bc087270e97e652 > > Author: Lucas Stach <[email protected]> > > Date: Fri Feb 17 20:02:44 2017 +0100 > > > > soc: imx: move PGC handling to a new GPC driver > > > > This is an almost complete re-write of the previous GPC power gating > > control > > code found in the IMX architecture code. It supports both the old and > > the new > > DT binding, allowing more domains to be added later and generally makes > > the > > driver easier to extend, while keeping compatibility with existing DTBs. > > > > As the result, all functionality regarding the power gating controller > > gets removed from the IMX architecture GPC driver. It keeps only the > > IRQ controller code in the architecture, as this is closely coupled to > > the CPU idle implementation. > > > > Signed-off-by: Lucas Stach <[email protected]> > > Signed-off-by: Shawn Guo <[email protected]> > > > > > > > > > > Then it could also address our issues and the binding would be > > > > still like: > > > > gpc: gpc@303a0000 { > > > > compatible = "fsl,imx7d-gpc"; > > > > reg = <0x303a0000 0x1000>; > > > > interrupt-controller; > > > > interrupts = <GIC_SPI 87 IRQ_TYPE_LEVEL_HIGH>; > > > > #interrupt-cells = <3>; > > > > interrupt-parent = <&intc>; > > > > > > > > pgc { > > > > #address-cells = <1>; > > > > #size-cells = <0>; > > > > > > > > pgc_pcie_phy: power-domain@IMX7_POWER_DOMAIN_PCIE_PHY { > > > > reg = <IMX7_POWER_DOMAIN_PCIE_PHY>; > > > > power-supply = <®_1p0d>; > > > > clocks = <xxx>; > > > > }; > > > > > > > > .... > > > > }; > > > > }; > > > > > > > > It also drops #power-domain-cells and register domain by > > > > one provider with multi domains which is more align with HW. > > > > > > > > How do you think of it? > > > > > > How is this more aligned with the hardware? Both options are an > > > arbitrary abstraction chosen in the DT binding. > > > > > > > GPC is a Power Controller which controls multi power domains to subsystem > > by its different registers bits. > > e.g. PCIE/MIPI/USB HSIC PHY. > > • 0xC00 ~ 0xC3F: PGC for MIPI PHY > > • 0xC40 ~ 0xC7F: PGC for PCIE_PHY > > • 0xD00 ~ 0xD3F: PGC for USB HSIC PHY > > > > So i thought it looks more like GPC is a power domain provider with multi > > domains support to different subsystems from HW point of view. > > > > Isn't that true? > > Linux and hardware devices are not required to match 1:1. There is > nothing that would make subdividing a single hardware device into > multiple ones bad style. > > > > > And there's also other two concerns: > > First, current genpd sysfs output still not include provider. > > e.g. > > root@imx6qdlsolo:~# cat /sys/kernel/debug/pm_genpd/pm_genpd_summary > > domain status slaves > > /device runtime status > > ---------------------------------------------------------------------- > > PU off-0 > > /devices/soc0/soc/130000.gpu suspended > > /devices/soc0/soc/134000.gpu suspended > > /devices/soc0/soc/2204000.gpu suspended > > /devices/soc0/soc/2000000.aips-bus/2040000.vpu suspended > > ARM off-0 > > > > I wonder it might be a bit mess once the provider is added while each > > domain is registered as a virtual provider. > > The provider is a Linux device. Linux devices don't necessarily have to > correspond to hardware devices. There is no such rule. > > > > > Second, it sacrifices a bit performance when look-up PM domain in > > genpd_get_from_provider if every domain is a provider. > > > The performance penalty of a list walk won't hurt us in the probe path, > where we are (re-)probing entire devices. There is a lot more going on > than a simple list walk. >
It is mostly care in a simulation platform like Zebu while the code execution time is quite long even it's very small in real word. > > Though it is arguable that currently only 3 domains support on MX7, > > but who knows the future when it becomes much more. > > > > However, i did see many exist users in kernel using one provider one > > domain way. Maybe i'm over worried and it's not big deal. > > I see that one provider with multiple domains is used more often, that > doesn't means it's necessarily better. At least I haven't hear a > convincing argument on why the chosen implementation in the GPC driver > is worse than the alternative. > Well, this is not a strong objection. I could also accept it if no objection from maintainer. And seems Shawn already picked the patches. So never mind, let's keep going on. Regards Dong Aisheg > Regards, > Lucas >
