Messages in this thread | | | Date | Wed, 30 Apr 2014 23:47:14 +0200 | Subject | Re: [PATCH/RFC 3/4] of/clk: Register clocks suitable for Runtime PM with the PM core | From | Geert Uytterhoeven <> |
| |
Hi Kevin,
On Sat, Apr 26, 2014 at 1:44 AM, Kevin Hilman <khilman@linaro.org> wrote: > Geert Uytterhoeven <geert+renesas@glider.be> writes: >> When adding a device from DT, check if its clocks are suitable for Runtime >> PM, and register them with the PM core. >> If Runtime PM is disabled, just enable the clock. >> >> This allows the PM core to automatically manage gate clocks of devices for >> Runtime PM. > > ...unless the device is already in an existing pm_domain, right?
At this point in the kernel boot process, the device cannot be in a pm_domain yet.
> I like this approach, and it extends nicely what we already do on > platforms using drivers/base/power/clock_ops.c into DT land. > > My only concern is how this will interact if it's used along with > devices that have existing pm_domains. I don't have any specific > concerns (yet, because it's Friday, and my brain is turing off), but it > just made me wonder if this will be potentially confusing.
Adding devices to pm_domains is done later, so it can be overridden.
> Also... > > [...] > >> +static int of_clk_register(struct device *dev, struct clk *clk) >> +{ >> + int error; >> + >> + if (!dev->pm_domain) { >> + error = pm_clk_create(dev); >> + if (error) >> + return error; >> + >> + dev->pm_domain = &of_clk_pm_domain; >> + } >> + >> + dev_dbg(dev, "Setting up clock for runtime PM management\n"); >> + return pm_clk_add_clk(dev, clk); > > I would've expected these 2 lines to be inside the pm_domain check. > > What's the reason for doing the pm_clk_add() when the pm_domain isn't > going to be used? I suppose it's harmless, but it's a bit confusing.
Sorry, the !dev->pm_domain check does deserve a comment explaining this. If there are multiple clocks suitable for pm_runtime, the pm_clk_create(dev) should be done only once.
Currently e.g. davinci registers 3 clocks with pm_clk ("fck", "master", and "slave"). Omap has 2 ("fck" and "ick").
BTW, keystone doesn't seem to set pm_clk_notifier_block.con_ids. From a quick look, this will crash with a NULL-pointer dereference in pm_clk_notify()? Or am I missing something here?
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
| |