On 04/28/2015 01:32 AM, Kevin Hilman wrote:
Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> writes:
On Fri, Apr 24, 2015 at 12:58 PM, Rajendra Nayak <rnayak@xxxxxxxxxxxxxx> wrote:
Second, I want to see less users of pm_clk_add_notifier() since it's
not the proper/long-term way of how to assign PM domain pointers to a
device. Instead that shall be done at device registration point. In
your case while parsing the DT nodes and adding devices onto to their
buses.
but these are devices which do not really have a controllable power
domain, they just have controllable clocks.
Yes, I understand that it will requires quite some work to adopt to
this behaviour - but that how it shall be done.
Finally, an important note, you don't need to use PM domains for these
devices at all and thus you don't need to fix what I propose. Instead
you only have to implement the runtime PM callbacks for each driver
and manage the clocks from there. That is probably also a easier
solution.
But that would mean I repeat the same code in all drivers to do a
clk_get/prepare/enable/disable/unprepare of the same "core" and "iface"
clocks. I thought we have clock_ops.c just to avoid that (atleast up
until we have a better way of doing it)
And there are atleast a few architecture which have used it to avoid the
duplication across all drivers (omap1/davinci/sh/keystone)
At least for arm/shmobile, we're planning to move away from this, cfr.
http://www.spinics.net/lists/linux-sh/msg41114.html
Just to clarify for Rajendra's sake...
SH is moving away from the pm_clk_add_notifier(), but not duplicating
the clk_get/prepare/enable/disable/unprepare across all the drivers.
Rather, they're using a genpd to model the clock domain, and taking
advantage of the pm_domain speciic attach callback to attach the PM
clocks.
This should work for qcom also assuming that these device nodes don't
also need to belong to a different PM domain.
Thanks Kevin, I did look up the patches that Geert pointed me to, and
figured I can do something similar for qcom as well like you said.
There are 2 types of devices that I will need to handle, one which have
clocks and also a power switch to turn the power domain on/off (camera,
graphics, display), and others which only have clocks and no power
switch to control the power domain (serial, sdhc, i2c, spi).
I was already using genpd attach/detach to handle clocks for the
devices with a power switch and genpd on/off to turn the PD on and off.
I guess I can also control the rest of the devices the same way, just
that the genpd on/off for them would do nothing.
That way I don't have to use pm_clk_add_notifier() and can also
associate the power domain (with no on/off control) to devices
through DT (and there isn;t any duplication of code in the drivers)
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