On Fri, 7 May 2021, at 13:00, Steven Lee wrote:

The 05/07/2021 09:40, Andrew Jeffery wrote:

quoted

On Thu, 6 May 2021, at 19:33, Steven Lee wrote:

quoted

Add the description for describing the AST2600-A2 EVB reference design of
GPIO regulators.

Signed-off-by: Steven Lee <redacted>
---
 arch/arm/boot/dts/aspeed-ast2600-evb.dts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed-ast2600-evb.dts 

b/arch/arm/boot/dts/aspeed-ast2600-evb.dts
index 2772796e215e..1ae0facc3d5f 100644

--- a/arch/arm/boot/dts/aspeed-ast2600-evb.dts
+++ b/arch/arm/boot/dts/aspeed-ast2600-evb.dts

@@ -104,6 +104,21 @@
 	status = "okay";
 };
 
+/*
+ * The signal voltage of sdhci0 and sdhci1 on AST2600-A2 EVB is able to be
+ * toggled by GPIO pins.
+ * In the reference design, GPIOV0 of AST2600-A2 EVB is connected to the
+ * power load switch that providing 3.3v to sdhci0 vdd, GPIOV1 is connected to
+ * a 1.8v and a 3.3v power load switch that providing signal voltage to
+ * sdhci0 bus.
+ * If GPIOV0 is active high, sdhci0 is enabled, otherwise, sdhci0 is disabled.
+ * If GPIOV1 is active high, 3.3v power load switch is enabled, sdhci0 signal
+ * voltage is 3.3v, otherwise, 1.8v power load switch will be enabled,
+ * sdhci0 signal voltage becomes 1.8v.
+ * AST2600-A2 EVB also support toggling signal voltage for sdhci1.
+ * The design is the same as sdhci0, it uses GPIOV2 as power-gpio and GPIOV3
+ * as power-switch-gpio.
+ */

Okay, I think the comment is in the right place, but I feel this patch 
should also add the regulator nodes and hook them up to the SDHCIs.

Given Rob isn't super keen on a second example in the binding document 
I think you can just cut the example out and paste it in here.

Hi Andrew,

Since AST2600-A0 and AST2600-A1 don't have regulators, do you mean cut
the example from dt-binding and paste it to aspeed-ast2600-evb.dts but
comment out the example?

If the board design varies with the silicon revision we should probably 
have devicetrees that are appropriate for each, so an 
aspeed-ast2600-evb-a2.dts

#include "aspeed-ast2600-evb.dts" at the top and go from there.

Cheers,

Andrew