Re: [RFC PATCH 6/7] mmc: sdhci-omap: Add OMAP SDHCI driver

Kishon Vijay Abraham I
2017-08-20T11:03:19Z

Adrian,

On Thursday 17 August 2017 01:53 PM, Adrian Hunter wrote:
> On 17/08/17 10:59, Kishon Vijay Abraham I wrote:
>> Hi Adrian,
>>
>> On Thursday 17 August 2017 12:13 PM, Adrian Hunter wrote:
>>> On 17/08/17 08:57, Kishon Vijay Abraham I wrote:
>>>> Hi Adrian,
>>>>
>>>> On Tuesday 15 August 2017 01:52 PM, Adrian Hunter wrote:
>>>>> On 07/08/17 19:01, Kishon Vijay Abraham I wrote:
>
> <SNIP>
>
>>>>>> + pm_runtime_enable(dev);
>>>>>> + ret = pm_runtime_get_sync(dev);
>>>>>
>>>>> What are you trying to do with runtime pm? There don't seem to be any pm
>>>>> callbacks, so does this do anything?
>>>>
>>>> yeah, pm_runtime_get_sync enables the functional clock and also configures the
>>>> SYSCONFIG regiters present in the controller. It gets the details for
>>>> configuring those from arch/arm/mach-omap2/omap_hwmod_*
>>>
>>> You mean it will do those things when you add the callbacks? I would prefer
>>> you leave out runtime pm until you can add the callbacks as well.
>>
>> No. Generally in callbacks, 'optional' functional clocks are enabled. But main
>> functional clock and interface clocks are enabled in pm_runtime_get_sync.
>> Without pm_runtime_get_sync, we won't be able to access controller registers.
>
> So that is done by the pm domain? Please add comments to the code to explain.

right, it's done by omap_device_pm_domain.
Invoking pm_runtime_get_sync of a platform device in OMAP platforms will
eventually come to omap_hwmod_enable where main functional clock, interface
clock and sysconfig are programmed.

Thanks
Kishon