[PATCH v3 1/2] Documentation: mmc: sdhci-of-arasan: add description of power domain

[Ziyuan Xu]

hi Ulf,


On 2016年09月17日 16:49, Ulf Hansson wrote:
> On 17 September 2016 at 04:32, Ziyuan Xu <xzy.xu at rock-chips.com> wrote:
>> Add power domain as a optional property for sdhci-of-arasan, which can
>> be turned off in the so-called unused condition, such as suspend and
>> remove. Aim to lower power requirements.
> I assume runtime suspend make sense as well?

Sorry to reply this mail after a long time.

On rk3399 platform, there is a eMMC-phy which is in charge of eMMC's 
logic interface. We should guarantee that phy is ready before cmd/data 
transfer.
I mean that I need to consider about the resume latency, so that I can 
land RPM for arasan-of-sdhci.
I intend to use auto-suspend for arasan-of-sdhci.

>
> Moreover, perhaps you could share a little information here about what
> needs to be done at the driver level which controls the mmc IP. More
> precisely, what do you need to do at runtime_suspend, suspend,
> runtime_resume, and resume?

Invoke sdhci_runtime_suspend_host, disable relevant clock in 
rumtime_suspend, deprocessing in runtime_resume.
Is that ok?

>
> Kind regards
> Uffe
>
>> Signed-off-by: Ziyuan Xu <xzy.xu at rock-chips.com>
>>
>> Acked-by: Rob Herring <robh at kernel.org>
>> ---
>>
>> Changes in v3:
>> - fix a typo
>> - add Rob's ack-tag
>>
>> Changes in v2:
>> - fix a typo
>> - add an example code for power-domain
>>
>>   Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> index 3404afa..eb84d29 100644
>> --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
>> @@ -1,12 +1,14 @@
>>   Device Tree Bindings for the Arasan SDHCI Controller
>>
>> -  The bindings follow the mmc[1], clock[2], interrupt[3] and phy[4] bindings.
>> +  The bindings follow the mmc[1], clock[2], interrupt[3], phy[4] and power
>> +  domain[5] bindings.
>>     Only deviations are documented here.
>>
>>     [1] Documentation/devicetree/bindings/mmc/mmc.txt
>>     [2] Documentation/devicetree/bindings/clock/clock-bindings.txt
>>     [3] Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
>>     [4] Documentation/devicetree/bindings/phy/phy-bindings.txt
>> +  [5] Documentation/devicetree/bindings/power/power_domain.txt
>>
>>   Required Properties:
>>     - compatible: Compatibility string.  One of:
>> @@ -36,6 +38,8 @@ Optional Properties:
>>     - #clock-cells: If specified this should be the value <0>.  With this property
>>       in place we will export a clock representing the Card Clock.  This clock
>>       is expected to be consumed by our PHY.  You must also specify
>> +  - power-domains: A phandle and PM domain as specifier defined by bindings
>> +    of the power controller specified by phandle.
>>
>>   Example:
>>          sdhci at e0100000 {
>> @@ -71,5 +75,6 @@ Example:
>>                  phys = <&emmc_phy>;
>>                  phy-names = "phy_arasan";
>>                  #clock-cells = <0>;
>> +               power-domains = <&power RK3399_PD_EMMC>;
>>                  status = "disabled";
>>          };
>> --
>> 2.9.2
>>
>>
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