Hi guys,
if i'm reading the code right, the PM clk means:
1/ the clocks which would be enabled while power on
2/ these clocks are optional, it's ok if anything wrong with them
3/ controlled by pm_domain(or USE_PM_CLK_RUNTIME_OPS & pm_clk_add_notifier)
and currently we're adding all clocks of the attached device as PM clk
in rockchip PM domain driver, which seems wrong. because we might have
these kinds of clocks:
1/ critical, should block power on if anything wrong with it(failed to
get/ prepare/ enable)
2/ optional, could ignore it if anything wrong
3/ only required in some special cases, for example register r/w, and
doesn't need to stay enabled while power on
so maybe we can:
1/ let the device(dts) or driver decide which clock is PM clk, and add
it using *pm_clk_add* APIs (even of_pm_clk_add_clks() if all clocks are
pm clk)
2/ add support for critical PM clk, which would return error to the
driver if anything wrong
3/ make sure PM clk always be controlled(otherwise it might be
unexpected disabled by other clocks under the same clk parent?):
a) make sure Runtime PM is always enabled. and as discussed, we can
select PM in ARCH_ROCKCHIP
b) make sure the device has a PM domain to control PM clk:
select ROCKCHIP_PM_DOMAINS for ARCH_ROCKCHIP(that would also select
PM_GENERIC_DOMAINS)
check dev->pm_domain before hand over PM clk, since we only care about
EPROBE_DEFER when attach PM domain:
ret = dev_pm_domain_attach(_dev, true);
if (ret != -EPROBE_DEFER) {
if (drv->probe) {
ret = drv->probe(dev);
or
c) make pm_clk_suspend/pm_clk_resume part of the generic PM Runtime
flow(even without a PM domain)
On 02/28/2018 10:07 PM, Tomasz Figa wrote:
> On Wed, Feb 28, 2018 at 10:11 PM, Geert Uytterhoeven
> <geert at linux-m68k.org> wrote:
>> Hi Tomasz,
>>
>> On Wed, Feb 28, 2018 at 1:49 PM, Tomasz Figa <tfiga at chromium.org> wrote:
>>> On Wed, Feb 28, 2018 at 9:32 PM, Geert Uytterhoeven
>>> <geert at linux-m68k.org> wrote:
>>>> On Wed, Feb 28, 2018 at 1:29 PM, Tomasz Figa <tfiga at chromium.org> wrote:
>>>>> Also, how about systems where runtime PM is disabled? I think that's
>>>>> one of the reasons we control the clocks explicitly in the drivers
>>>>> anyway.
>>>>
>>>> On many platforms, Runtime PM is always enabled.
>>>
>>> Can we make such assumption? If so, could we just make an explicit
>>> "select PM_RUNTIME" in Kconfig of the SoC?
>>
>> Note that the PM_RUNTIME symbol was removed in commit 464ed18ebdb6236f
>> ("PM: Eliminate CONFIG_PM_RUNTIME"), in favor of plain PM.
>>
>> The following already select PM unconditionally:
>> - ARCH_OMAP2PLUS_TYPICAL
>> - ARCH_RENESAS (except EMEV2)
>> - ARCH_TEGRA
>> - ARCH_VEXPRESS
>
> Thanks! Sounds like we might be able to simplify a lot of things with
> doing the same for Rockchip.
>
> Best regards,
> Tomasz
>
>
>
