On Fri, Jun 15, 2018 at 7:43 PM, Stephen Boyd <sboyd@xxxxxxxxxx> wrote: > Quoting Rafael J. Wysocki (2018-06-13 01:27:39) >> On Wed, Jun 13, 2018 at 10:13 AM, Andy Shevchenko >> <andy.shevchenko@xxxxxxxxx> wrote: >> > +Cc: Rafael, ACPI ML >> > >> > On Wed, Jun 13, 2018 at 7:14 AM, Srinath Mannam >> > <srinath.mannam@xxxxxxxxxxxx> wrote: >> >> Hi Michael, Stephen, >> >> >> >> We are adding ACPI support in our Linux based platform. >> >> At present our clock hierarchy using common clock framework through DTS. >> >> Now we required ACPI support in common clock framework to upgrade our platform. >> >> >> >> For example, clk_get API called in many drivers to get clock device is >> >> tightly coupled with DT framework. >> >> >> >> Please let us know, if anybody in Open Source community have plans to >> >> add ACPI support for common clock framework. >> >> There are no plans for doing that AFAICS. >> >> Moreover, it generally would not be consistent with ACPI power >> management defined by the specification. > > This matches my understanding. > >> >> >> If not please suggest us alternative method to use common clock >> >> framework in ACPI use case. >> >> The problem with using the clock framework on systems with ACPI is >> that, in general, the clock manipulation is expected to be carried out >> by ACPI power management and therefore it is "owned" by AML. >> Currently, there are no defined methods for synchronizing the AML's >> use of clocks for power management with what the OS may do with them >> directly. >> >> In theory, that can be worked around to some extent by representing >> clocks as power resources in ASL (even though the provider information >> would be missing then) and manipulating those power resources directly >> from the OS. I'm not aware of anyone doing that successfully, >> however. >> >> For simple power management it should be sufficient to let drivers >> rely on the ACPI PM domain which should happen automatically in the >> majority of cases anyway. >> > > Is this for clk_enable/disable? What about clk_set_rate() or > clk_set_phase()? Is ACPI's AML taking care of that? That's for clk_enable/disable AFAICS. AML doesn't manage device performance states at all. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
