[PATCH 1/4] Documentation: mmc: sdhci-of-arasan: Add clk_syscon as an optional one

Rob Herring robh at kernel.org
Fri Sep 2 07:15:08 PDT 2016

On Mon, Aug 29, 2016 at 04:02:56PM +0800, Shawn Lin wrote:
> We introduced soc-ctl-syscon to do several things, for instance, update
> baseclk or update clkmul, etc. In odrder to access this physical block,
> we need to explicitly enable its clock. Currently we don't control this
> clock as we always add a CLK_IGNORE_UNUSED flag for it to indicate that
> we will not gate it even if not referenced. This is not a correct way since
> it is a clock parenting from clk_ahb which is used by sdhci-of-arasan now.
> Without enabling clk_ahb, the flag don't guarantee we could access
> soc-ctl-syscon. Moreover, we can't find a reason not to gate clk_syscon
> once we remove/power-down emmc controller. So let's add clk_syscon and
> enable/disable it explicitly when needed.
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
> ---
>  Documentation/devicetree/bindings/mmc/arasan,sdhci.txt | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> index 3404afa..b04eb02 100644
> --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> @@ -33,6 +33,9 @@ Optional Properties:
>    - clock-output-names: If specified, this will be the name of the card clock
>      which will be exposed by this device.  Required if #clock-cells is
>      specified.
> +  - clock-names: From clock bindings: Although we treat clock-names as required
> +    property, there is still one, "clk_syscon", should be optional as it depends
> +    on whether we need to control soc-ctl-syscon or not.

No. This doesn't look right to me. The syscon is a separate block 
and the clock for it belongs in the syscon node itself. Probably there 
needs to be some sort of ref counting in the syscon so it can do 


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