Re: [PATCH 2/2] thermal: rcar_thermal: use pm_runtime_put_sync()
From: Geert Uytterhoeven
Date: Tue Nov 10 2015 - 05:11:02 EST
On Tue, Nov 10, 2015 at 10:57 AM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 10 November 2015 at 09:18, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>> On Tue, Nov 10, 2015 at 3:12 AM, Kuninori Morimoto
>> <kuninori.morimoto.gx@xxxxxxxxxxx> wrote:
>>> From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
>>> It is using pm_runtime_get_sync() on probe(). Let's use
>>> pm_runtime_put_sync() instead of pm_runtime_put(). Otherwise thermal
>>> sensor doesn't work after unbind/re-bind
>>> Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
>>> drivers/thermal/rcar_thermal.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> diff --git a/drivers/thermal/rcar_thermal.c b/drivers/thermal/rcar_thermal.c
>>> index 13d01ed..f7cf2d7 100644
>>> --- a/drivers/thermal/rcar_thermal.c
>>> +++ b/drivers/thermal/rcar_thermal.c
>>> @@ -373,7 +373,7 @@ static int rcar_thermal_remove(struct platform_device *pdev)
>>> - pm_runtime_put(dev);
>>> + pm_runtime_put_sync(dev);
> For the reasons explained by Geert, this is to me also a "workaround".
> I would replace pm_runtime_put() and pm_runtime_disable() with a call
> to pm_runtime_force_suspend().
> In that way, you will make sure you device get runtime suspended
> (clock domain will gate the clock). Additionally, the runtime PM
> status will properly reflect the status of the device.
That still sounds like a workaround to me, which we have to apply to all
drivers relying on Runtime PM?
>> With a bit more debugging info, this is the difference between the failing
>> and the "fixed" cases:
>> +rcar_thermal e61f0000.thermal: pm_clk_suspend()
>> +renesas-cpg-mssr e6150000.clock-controller: MSTP 522/thermal OFF
>> rcar_thermal e61f0000.thermal: removing from PM domain clock-controller
>> pm_genpd_remove_device: Remove e61f0000.thermal from clock-controller
>> -renesas-cpg-mssr e6150000.clock-controller: MSTP 522/thermal OFF
>> rcar_thermal e61f0000.thermal: adding to PM domain clock-controller
>> __pm_genpd_add_device: Add e61f0000.thermal to clock-controller
>> rcar_thermal e61f0000.thermal: Clock thermal con_id (null) managed by
>> runtime PM.
>> -rcar_thermal e61f0000.thermal: thermal sensor was broken
>> +rcar_thermal e61f0000.thermal: pm_clk_resume()
>> +renesas-cpg-mssr e6150000.clock-controller: MSTP 522/thermal ON
>> rcar_thermal e61f0000.thermal: 1 sensor probed
>> In the failing case, pm_clk_suspend() is not called, and turning off the
>> module clock is thus delayed until removal of the device from the clock
>> But as pm_clk_suspend() wasn't called, the device isn't correctly resumed on
>> rebind, and the module clock is never re-enabled, leading to a failure.
>> Ulf, what do you think?
> I totally agree on your analyse.
> The problem is that the runtime PM status of the device isn't
> correctly updated at ->remove(). The effect is that the the
> pm_runtime_get_sync() in ->probe() at re-bind will *not* trigger the
> ->runtime_resume() callbacks to be invoked, as the runtime PM core
> believes the device is already runtime resumed.
So that's where it should be fixed?
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/