On 10.06.2014 23:27, Greg Kroah-Hartman wrote: > On Tue, Jun 10, 2014 at 11:27:45PM +0200, Rafael J. Wysocki wrote: >> On Tuesday, June 10, 2014 02:53:26 PM Ulf Hansson wrote: >>> On 10 June 2014 14:11, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: >>>> On Tue, Jun 10, 2014 at 12:51 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: >>>>> From: Tomasz Figa <t.figa@xxxxxxxxxxx> >>>>> >>>>> On a number of platforms, devices are part of controllable power >>>>> domains, which need to be enabled before such devices can be accessed >>>>> and may be powered down when the device is idle to save some power. >>>>> This means that on systems that support power domain control using >>>>> generic power domains subsystem, it is necessary to add device to its >>>>> power domain before binding a driver to it and remove it from its power >>>>> domain after its driver is unbound to make sure that an unused device >>>>> does not affect power domain state. >>>>> >>>>> Since this is not limited to particular busses and specific >>>>> archs/platforms, >>>> >>>> Actually, this isn't correrct. It is limited to the platforms that >>>> use Device Trees now. >>> >>> Correct, we should update the commit message/docs. >>> >>>> >>>> Moreover, it is not consistent with the way we add devices to the ACPI PM >>>> domain, which is the ACPI counterpart of this. >>> >>> I am not sure why you think consistency for ACPI is important here. >>> ACPI PM will still be able to handle it's domain/device registering as >>> before. There are even other pm_domains that don't use genpd which >>> need to handle this themselves. >> >> My point is that doing things like that in different places for different >> firmware interfaces is confusing and likely to lead to coding mistakes in >> the future. >> >>> Or are you saying that you prefer bus notifiers in favour of making >>> use of the driver core for this matter? >> >> Well, please grep for acpi_dev_pm_attach() and see where it is done. >> Surely not in drivers/base/dd.c. Also I'm not sure why you're talking >> about bus notifiers in this context. >> >>> Shouldn't the driver core handle most of the common things for a device >>> driver? >> >> Common, yes. Platform-specific, no. >> >>> Let's compare how the pinctrls are being managed in the driver core, for >>> example. >> >> pinctrl has Device Trees support only at the moment (as far as firmware >> interfaces go) and quite frankly I'm not sure if/how we'll need to change >> it to cover ACPI as well. >> >> But for power domains, please keep that stuff away from dd.c. That is, >> unless Greg specifically disagrees with me and decides to apply this >> patch regardless. :-) > > Nope, no disagreement from me toward you at all here, keep up the good > work :) OK, so proposed solution is to put this in: - platform_drv_probe(), - spi_drv_probe(), - i2c_device_probe(), - amba_probe(), ... - and any other bus type, which can have devices instantiated from DT. If this is what you mean, I still think putting this in dd is cleaner and more scalable, but I'm not going to insist, as I believe you have good reasons to prefer this approach over current one. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
