2013/4/22 Tomasz Figa t.figa@samsung.com
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 management fully.This
> is same as only the use of pm runtime interface(needing some hard > 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 hardware mustbe
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.
Again. There is any case that the driver isn't worked correctly without CONFIG_PM_RUNTIME and with clk_enable(). Could you guarantee the driver to be worked correctly only adding clk_enable() to probe() without CONFIG_PM_RUNTIME? as I said before, what if the power domain to the device was disabled?
Rafael, Kevin, do you have any opinion on this?
Best regards,
Tomasz Figa Samsung Poland R&D Center SW Solution Development, Kernel and System Framework
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