On Wed, Nov 28, 2018 at 6:33 PM Maxime Ripard [off-list ref] wrote:

On Wed, Nov 28, 2018 at 05:30:01PM +0800, Chen-Yu Tsai wrote:

quoted

Experiments showed that on at least the H3/H5/A64 the RTC's internal
oscillator also feeds the CPUS mux in the PRCM.

Export this clock through the device tree, instead of having to use
a dummy fixed-clock device node, for the PRCM to consume. This will
properly describe the relationship between the clocks.

Signed-off-by: Chen-Yu Tsai <redacted>
---
 Documentation/devicetree/bindings/rtc/sun6i-rtc.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/rtc/sun6i-rtc.txt b/Documentation/devicetree/bindings/rtc/sun6i-rtc.txt
index 78c4fb472eb7..1bd37faadecb 100644
--- a/Documentation/devicetree/bindings/rtc/sun6i-rtc.txt
+++ b/Documentation/devicetree/bindings/rtc/sun6i-rtc.txt

@@ -24,7 +24,7 @@ Required properties:

 Required properties for new device trees
 - clocks     : phandle to the 32kHz external oscillator
-- clock-output-names : names of the two clock outputs. See below.
+- clock-output-names : names of the three clock outputs. See below.
 - #clock-cells  : must be equal to 1.

 The RTC provides the following clocks at the given indices:

@@ -32,6 +32,7 @@ The RTC provides the following clocks at the given indices:
 - 1: LOSC external output, known as X32KFOUT in the datasheet.
      This clock is not available on the A31 and is deprecated for old
      device trees still using the "allwinner,sun6i-a31-rtc" compatible.
+- 2: InternalOSC, or internal RC oscillator

It seems to be required only for a few RTC though (H3, H5 and R40?)

IMO there's no harm in exporting it for all SoCs. I still don't know
if it's needed for the A31 either. And we don't have documents for the
PRCM stuff for any of the SoCs involved.

ChenYu