2013/4/22 Rafael J. Wysocki rjw@sisk.pl
On Monday, April 22, 2013 12:37:36 PM Tomasz Figa wrote:
On Monday 22 of April 2013 12:17:39 Sylwester Nawrocki wrote:
On 04/22/2013 12:03 PM, Inki Dae wrote:
> Also looks good to me. But what if power domain was disabledwithout
> pm > runtime? In this case, you must enable the power domain atmachine
> code or > bootloader somewhere. This way would not only need some hardcodes
> to turn > the power domain on but also not manage power managementfully. This
> is same as only the use of pm runtime interface(needing somehard
> codes without pm runtime) so I don't prefer to add > clk_enable/disable to fimd probe(). I quite tend to force onlythe
> use of pm runtime as possible. So please add the hard codes to > machine code or bootloader like you did for power domain if you > want to use drm fimd without pm runtime. That's not how the runtime PM, clock subsystems work: 1) When CONFIG_PM_RUNTIME is disabled, all the used hardwaremust be
kept powered on all the time. 2) Common Clock Framework will always gate all clocks that havezero
enable_count. Note that CCF support for Exynos is already mergedfor
3.10 and it will be the only available clock support method for Exynos. AFAIK, drivers must work correctly in both cases, with CONFIG_PM_RUNTIME enabled and disabled.Then is the driver worked correctly if the power domain to this
device was
disabled at bootloader without CONFIG_PM_RUNTIME and with
clk_enable()? I
think, in this case, the device wouldn't be worked correctly because
the
power of the device remains off. So you must enable the power domain somewhere. What is the difference between these two cases?
How about making the driver dependant on PM_RUNTIME and making it
always
use pm_runtime_* API, regardless if the platform actually implements
runtime
PM or not ? Is there any issue in using the Runtime PM core always,
rather
than coding any workarounds in drivers when PM_RUNTIME is disabled ?
I don't think this is a good idea. This would mean that any user that
from
some reasons don't want to use PM_RUNTIME, would not be able to use the
driver
anymore.
Rafael, Kevin, do you have any opinion on this?
I agree.
Drivers should work for CONFIG_PM_RUNTIME unset too and static inline stubs for all runtime PM helpers are available in that case.
Hi Rafael,
The embedded system, at least Exynos SoC case, has the power domain device and this device could be enabled only by pm runtime interface. So the device couldn't be worked correctly without turning the power domain on only calling clk_enable(). In this case, the power domain must be enabled at machine code or bootloader. And the machine without CONFIG_PM_RUNTIME would assume that their own drivers always are enabled so the devices would be worked correctly. Is there any my missing point?
Thanks, Inki Dae
Thanks,
Rafael
-- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html