Hi Rob,

On Thu, 2019-03-14 at 03:48 +0800, Rob Herring wrote:

On Tue, Mar 12, 2019 at 9:41 PM Stanley Chu [off-list ref] wrote:

quoted

Hi Rob,

On Tue, 2019-03-12 at 21:31 +0800, Rob Herring wrote:

quoted

On Wed, Feb 27, 2019 at 03:23:10PM +0800, Stanley Chu wrote:

quoted

Add UFS and UFS PHY node document for Mediatek SoC chips.

Signed-off-by: Stanley Chu <stanley.chu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 .../devicetree/bindings/ufs/ufs-mediatek.txt  | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/ufs/ufs-mediatek.txt

diff --git a/Documentation/devicetree/bindings/ufs/ufs-mediatek.txt b/Documentation/devicetree/bindings/ufs/ufs-mediatek.txt
new file mode 100644
index 000000000000..5fc985928b3e
--- /dev/null
+++ b/Documentation/devicetree/bindings/ufs/ufs-mediatek.txt

@@ -0,0 +1,47 @@
+* Mediatek Universal Flash Storage (UFS) Host Controller
+
+UFS nodes are defined to describe on-chip UFS hardware macro.
+Each UFS Host Controller should have its own node.
+
+To bind UFS PHY with UFS host controller, the controller node should
+contain a phandle reference to UFS M-PHY node.
+
+Required properties for UFS nodes:
+- compatible         : Compatible list, contains the following controller:
+                       "mediatek,ufshci"

Needs an SoC specific compatible string.

Will add.

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+- reg                : Address and length of the UFS register set.
+- interrupt-parent   : Interrupt device.

Drop this. It is implied or may be in a parent node.

Will remove it.

quoted

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+- phys               : phandle to m-phy.
+- clocks             : List of phandle and clock specifier pairs.
+- clock-names        : List of clock input name strings sorted in the same
+                       order as the clocks property. "ufs-clk" is mandatory.
+- freq-table-hz      : Array of <min max> operating frequencies stored in the same
+                       order as the clocks property. If this property is not
+                       defined or a value in the array is "0" then it is assumed
+                       that the frequency is set by the parent clock or a
+                       fixed rate clock source.
+- vcc-supply         : Power to the UFS device.
+- vcc-fixed-regulator: Specify that vcc-supply is a fixed regulator.

Why is this needed? The driver could query the voltage range of the
regulator or you could check the regulator node.

Both ufshcd-pltfrm.txt and ufshcd-pltfrm.c driver allow

- <name>-fixed-regulator : boolean property specifying that
<name>-supply is a fixed regulator.

Our vcc does not require further initializatio, so is it OK here or
shall we also modify both ufshcd-pltfrm dt-bindings document and ufs
driver to avoid using it ?

There are no users of that property in tree and doesn't look like
adding it was ever reviewed. We have standard ways to handle this and
don't need a custom property.

Got it and thanks.

I am planning to drop VCC related first in this series and add it back
by another patch accompanied with VCC/ICC logic fix in UFS common driver
which beyond the scope of this series.

Rob

Thanks,
Stanley.