[RFC PATCH 0/2] use named clocks list to register clocks for PM clock domain

Grygorii Strashko
2014-06-12T16:06:51Z

Hi Geert,

I've spent some time testing your patches on Keystone 2 SoC as I am interested
in these patches.

The Keystone 2 is pure DT platform, but we reuse some Drivers from Davinci SoC.
Now I have to dial with following problem:
- Some modules on Keystone need more then one clock to be managed by PM clock.
As result, I can solve this by filling cond_id list in structure
pm_clk_notifier_block.
For example:
static struct pm_clk_notifier_block platform_domain_notifier = {
.pm_domain = &keystone_pm_domain,
.con_ids = { "fck", "master", "slave", NULL },
};
But, in this case I'll need to add names for all clocks or rename existed
clock's names in DT to be compatible with above list, like:
clock-names = "gpio"; -> clock-names = "fck";
- or -
clocks = <&clkspi>;
+ clock-names = "fck";

Your series gracefully solves this problem for me, but I'd like to avoid
to use new CLK flag CLK_RUNTIME_PM, because:
- The same driver is used for all gated clocks for Keystone (and probably for
other SoCs)
- Some gated clocks can be optional.
Taking into account above, driver for gated clock will need to maintain additional
information internally about clocks which are suitable for Runtime PM -
it is too hard to support :(.

Therefore, I propose a solution which allows to specify clocks suitable for
Runtime PM in DT using special property "clkops-clocks" (name can be changed:).

Another possible option is to use DT definition like this:
spi2: spi@21000800 {
compatible = "ti,dm6441-spi";
reg = <0x21000800 0x200>;
num-cs = <4>;
ti,davinci-spi-intr-line = <0>;
interrupts = <GIC_SPI 300 IRQ_TYPE_EDGE_RISING>;
-> clkops-clocks {
-> clocks = <&clkspi>;
-> }
}

Regarding supporting of EPROBE_DEFER, in my opinion simplest solution would be to
call of_clk_register_runtime_pm_clocks() directly from drivers.
Another option 1, call of_clk_register_runtime_pm_clocks() before driver's probing
seems will be banned by Greg and Rafael.
Another option 2, continue to use Bus notifiers, but then error path need to be
handled somehow. Now BUS_NOTIFY_BIND_DRIVER even is sent before probing, but
it seems that nothing is sent in case if probe was failed.

Grygorii Strashko (2):
clk: of: introduce of_clk_get_from_set()
of/clk: use "clkops-clocks" to specify clocks handled by clock_ops
domain

drivers/clk/clkdev.c | 24 ++++++++++++++++++++++--
drivers/of/of_clk.c | 7 ++-----
include/linux/clk.h | 7 +++++++
3 files changed, 31 insertions(+), 7 deletions(-)

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1.7.9.5