[linux-sunxi] [PATCH] arm64: dts: allwinner: Revert SD card CD GPIO for Pine64-LTS

[Daniel Kulesz]

Hi folks,

I have just made the two changes suggested by Michael to my A64-LTS. My unit is running kernel 5.10.28-1 from Debian unstable (Package "linux-image-5.10.0-6-arm64"). The DTB was built from the one supplied with kernel 5.10.29 (from kernel.org).

Using the modified dtb (with the changes applied), the machine *DOES* boot fine for me.

Cheers, Daniel


On Tue, 13 Apr 2021 20:48:24 +0200
Michael Weiser <michael.weiser at gmx.de> wrote:

> Hi Jernej and Andre,
> 
> On Tue, Apr 13, 2021 at 11:58:37AM +0100, Andre Przywara wrote:
> 
> > > > Daniel, Michael, can you test this on your boards? So removing the
> > > > cd-gpios property, and adding "broken-cd;" instead?  
> > > Yes, it works fine. What flummoxed me at first was that obviously I also
> > > have to disable the ACTIVE_LOW definition in sun50i-a64-sopine.dtsi
> > > after having added and disabled an ACTIVE_HIGH definition in
> > > sun50i-a64-pine64-lts.dts.
> > Why? From my experiments it should not matter, the actual card presence
> > is typically detected via the SD bus anyway (if I understand the code
> > correctly). broken-cd just prevents installation of an interrupt
> > handler, so it's less efficient and prevents wakeup on card detect,
> > AFAICS.
> 
> I just retested to be sure: At least with 5.11.11 and on my boards,
> cd-gpio ACTIVE_LOW being specified in the sopine.dtsi takes precedence
> over broken-cd being specified in pine64-lts.dts. Could that spoil the
> plan of disabling cd-gpio for the LTS while leaving it enabled for
> Sopine and baseboard?
> 
> Behaviour is as such: With cd-gpios ACTIVE_LOW in sopine.dtsi and
> broken-cd in pine64-lts.dts, card insertion, removal and reinsertion is
> not detected after booting the kernel without a card in the slot. With
> cd-gpios ACTIVE_LOW removed from sopine.dtsi it starts working.
> 
> In diffs for added clarity:
> 
> PAGER= git log --pretty=oneline HEAD~1..HEAD
> aa7258f8f3d48a29bc024ea8c5145bdc4a980e4d (HEAD, tag: v5.11.11) Linux 5.11.11
> 
> - not working on its own:
> 
> index 302e24be0a31..5b0c21e68352 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64-pine64-lts.dts
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-pine64-lts.dts
> @@ -8,3 +8,7 @@ / {
>         compatible = "pine64,pine64-lts", "allwinner,sun50i-r18",
>                      "allwinner,sun50i-a64";
>  };
> +
> +&mmc0 {
> +       broken-cd;
> +};
> 
> - working with this additional change:
> 
> index 3402cec87035..ba2b7398993b 100644
> --- a/arch/arm64/boot/dts/allwinner/sun50i-a64-sopine.dtsi
> +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-sopine.dtsi
> @@ -34,7 +34,6 @@ &mmc0 {
>         vmmc-supply = <&reg_dcdc1>;
>         disable-wp;
>         bus-width = <4>;
> -       cd-gpios = <&pio 5 6 GPIO_ACTIVE_LOW>; /* PF6 */
>         status = "okay";
>  };
> 
> > So for your particular board (version) you could actually remove the
> > whole &mmc0 node override, use the same node as the SOPine (working
> > active-high CD) and it should work.
> 
> Correct. Again for reasons of laziness I tested with the dts from
> 5.11.11 which is currently running on the board and which still has
> ACTIVE_LOW in sopine.dtsi. Sorry for not being clearer about that.
> 
> But somewhat lucky as well because without ACTIVE_LOW still being set in
> sopine.dtsi I wouldn't have had a way to tell that broken-cd was not
> taking effect and silently have tested the working ACTIVE_HIGH
> definition from sopine.dtsi.
> 
> Or am I somehow making a mess of this?
> 
> > > BTW: My boards have a marking "PINE64-R18-V1_1" and below it
> > > "2017-08-03" on their upper side. On the back it says on one sticker
> > > "Model:PineA64 2GB LTS" and on another "2O1-PINE64R18-00" and
> > > "PINE64-R18-V1.1 2G". Is CD being stuck at 1 a bug of revision 1.0
> > > perhaps?  Is there a way to detect this difference in software and add
> > > some sort of quirk handler for it?
> > As Jernej mentioned, this would be U-Boot's task, but I don't see a
> > good reason for it. Firstly, you would need to find a good automatic
> > way of determining the board revision, which I doubt there is. And
> > secondly, I don't see the benefit: It works quite nicely with
> > broken-cd: card removals and insertions are detected automatically,
> > it's just not as efficient (interrupt-driven) as it could be.
> > Or do you see any problems with broken-cd?
> 
> Of course not. My boards have their rootfs on mmc0, so the card is never
> removed and replaced during operation anyway. I was just asking out of
> curiosity.
> 
> And out of curiosity again: Could one have a device tree overlay
> configured manually to be loaded by the bootloader that adds cd-gpio
> ACTIVE_HIGH for mmc0 and disables/overrules broken-cd? Somewhat like so
> (untested):
> 
> /dts-v1/;
> /plugin/;
> 
> #include <dt-bindings/gpio/gpio.h>
> 
> / {
>         fragment at 0 {
>                 target = <&mmc0>;
>                 __overlay__ {
>                         cd-gpios = <&pio 5 6 GPIO_ACTIVE_HIGH>; /* PF6 push-push switch */
>                 };
>         };
> };
> 
> Here it would be useful if cd-gpios indeed took precedence over
> broken-cd because my grepping of the code can't find a way to un-specify
> it once set.
> -- 
> Michael


-- 
Daniel Kulesz <daniel.kulesz at posteo.de>
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