Re: [PATCH 2/2] mmc: sdhci-pci: add runtime pm support

[Ulf Hansson <ulf.hansson@stericsson.com>]

> 
> It has been discussed on the list before that the host controller driver should 
> be solely responsible for host controller power.

OK I see, sorry that I missed that discussion earlier!

Anyway this should be feasible as well even it might mean duplicated 
code in each host driver. A positive side is that it gets more flexible 
for each host driver.

> 
>>
>> Moreover 1:
>> I have noticed the pm_runtime support is implemented for sdio and when having
>> MMC_CAP_POWER_OFF_CARD. This needs to be "cleaned up" after such a change. It
>> might also conflict with your patch considering "moreover 2" below.
> 
> No.  The card and the host controller are separate devices.  The card can be 
> powered up when the host controller is off and vice versa.  They are not 
> inter-dependent in that regard.

I see your point, but it is somewhere here it is getting a bit "messy". :-)

If I understand correct, you mean that the mmc/sd/sdio framework shall
be responsible of handling power management of the bus/card devices. In
other words the framework shall itself decide when it is feasible of
doing mmc_power_restore_host, mmc_power_save_host, mmc_suspend_host,
mmc_resume_host.

This is not the case right now, since most host drivers are normally in
control of calling these functions themselves. Should this be moved to 
the framework then?

> 
>> Moreover 2:
>> dev_pm_ops with runtime functions, are implemented for the mmc bus (core/bus.c).
>> Maybe this should be moved from the responsibility of the bus into the mmc host
>> drivers instead!? I think it makes more sense to leave such decisions as doing
>> "mmc_power_save_host/mmc_power_restore_host" to each mmc host driver. Just
>> because we get runtime suspended that does not have to mean we wnat to do
>> mmc_power_save_host... What do you think?
> 
> Again, this has been discussed before on the list, that the power management of 
> the card is something that only upper layers control e.g. sdio function driver
> 

I got it, thanks a lot for your answers and feedback!


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BR
Ulf Hansson