On 2020-02-01 3:41 pm, Adam Van Ymeren wrote:

On 2020-02-01 5:51 a.m., Robin Murphy wrote:

quoted

Hi Adam,

On 2020-01-31 11:38 pm, Adam Van Ymeren wrote:

quoted

With this change the kernel successfully finds the SD Card and can load
a rootfs from it.  Tested on hardware.

Signed-off-by: Adam Van Ymeren <redacted>

diff -uprN -X linux-5.5/Documentation/dontdiff
linux-5.5-orig/arch/arm64/boot/dts/rockchip/rk3328-roc-cc.dts
linux-5.5/arch/arm64/boot/dts/rockchip/rk3328-roc-cc.dts

--- linux-5.5-orig/arch/arm64/boot/dts/rockchip/rk3328-roc-cc.dts

2020-01-26 19:23:03.000000000 -0500

+++ linux-5.5/arch/arm64/boot/dts/rockchip/rk3328-roc-cc.dts

2020-01-31 16:26:35.377075419 -0500

@@ -44,7 +44,7 @@
         vcc_sdio: sdmmcio-regulator {
           compatible = "regulator-gpio";
-        gpios = <&grf_gpio 0 GPIO_ACTIVE_HIGH>;
+        gpios = <&gpio0 RK_PD1 GPIO_ACTIVE_HIGH>;

Given that the RK3328 datasheet has no mention of GPIO0_D1 existing at
all, how sure are you that this is correct - have you tested cards in
both 3.3V and 1.8V (UHS-1) signalling modes?

The ROC-RK3328-CC schematics show GPIO_MUTE being used to bias the
feedback pin of an adjustable regulator supplying the SDMMC0 I/O
domain, so it seems more likely that the pin is correct but the states
(or the polarity) are backwards.

Hmm yeah after reading the schematics this doesn't make sense.  I took
it from the vendors source tree[1], and it definitely allowed my system
to boot when it wouldn't before, but I only tried a 3.3V card.  I'll try
just changing the polarity.  I'll also find a UHS-1 card and test that,
any advice on how to verify that it's running in the 1.8V mode?

My preferred method is to stick a meter on either the uSD socket pins or 
the regulator itself and wiggle the GPIO from userspace, but preferably 
only if the board can run without a card inserted.

That said, I just suddenly remembered about regulator GPIOs being quirky 
for legacy ABI reasons - I'm now 99% sure that you should simply need to 
add the "enable-active-high" property to make it actually work as expected.

Robin.

[1]
https://github.com/FireflyTeam/kernel/blob/rk3328/firefly/arch/arm64/boot/dts/rockchip/rk3328-firefly-core.dtsi#L89


Thanks for the review!

-Adam

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