[PATCH] ARM: dts: BCM5301X: Fix pin controller node
Rafał Miłecki
zajec5 at gmail.com
Thu Aug 20 08:20:21 EDT 2020
On 19.08.2020 06:23, Florian Fainelli wrote:
> The pin controller resources start at 0xc0 from the CRU base which is at
> 0x100 from th DMU base, for a final address of 0x1800_c1c0, whereas we
> are currently off by 0x100. The resource size of the CRU is also
> incorrect and should end at 0x248 bytes from 0x100 which is the start
> address. Finally, the compatibility strings defined for the
> pin-controller node should reflect the SoC being used.
I can confirm 0x1800c1c0 is the correct absolute offset.
> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi
> index 2d9b4dd05830..bf49943f504a 100644
> --- a/arch/arm/boot/dts/bcm5301x.dtsi
> +++ b/arch/arm/boot/dts/bcm5301x.dtsi
> @@ -402,14 +402,14 @@ dmu at 1800c000 {
>
> cru at 100 {
> compatible = "simple-bus";
> - reg = <0x100 0x1a4>;
> + reg = <0x100 0x248>;
> ranges;
> #address-cells = <1>;
> #size-cells = <1>;
>
> - pin-controller at 1c0 {
> - compatible = "brcm,bcm4708-pinmux";
> - reg = <0x1c0 0x24>;
> + pinctrl: pin-controller at c0 {
> + compatible = "brcm,bcm53012-pinmux";
> + reg = <0xc0 0x24>;
> reg-names = "cru_gpio_control";
>
> spi-pins {
>
That whole binding has a bit messy story.
Initially it used to be binding like:
compatible = "brcm,bcm4708-pinmux";
reg = <0x1800c1c0 0x24>;
reg-names = "cru_gpio_control";
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c12fb1774deaa9c9408b19db8d43d3612f6e47a0
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f9f82b3ffb8bfe01988c890e3a24328e9e1c1df
Later example binding was rewritten to include dmu and cru (simplified
below):
dmu at 1800c000 {
compatible = "simple-bus";
ranges = <0 0x1800c000 0x1000>;
cru at 100 {
compatible = "simple-bus";
reg = <0x100 0x1a4>;
ranges;
pin-controller at 1c0 {
compatible = "brcm,bcm4708-pinmux";
reg = <0x1c0 0x24>;
reg-names = "cru_gpio_control";
};
};
};
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=93d39737b29eaf1974bf850ccdc903b2418c800b
I don't understand or remember why pin-controller reg was relative to
dmu instead of cru. Some DT offset calculation magic?
Finally I updated binding to use "offset", see:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2ae80900f239484069569380e1fc4340fd6e0089
and then updated driver to follow:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a49d784d5a8272d0f63c448fe8dc69e589db006e
but I never updated DTS file accordingly.
To OpenWrt I pushed relevant kernel patch in the commit:
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commitdiff;h=a28f6ab27f9ae1a08c6945013cdb796b12ce150d
(called [PATCH] ARM: dts: BCM5301X: Update Northstar pinctrl binding)
but I never sent it upstream.
Florian: your change doesn't match docs or existing Linux driver:
1. Driver seems to ignore "reg"
2. Driver requires "offset"
3. Property "cru_gpio_control" is leftover (undocumented and unused)
I think we need to take a step back and cleanup Northstar bindings. Few
months ago I sent e-mail:
Subject: Proper DT bindings for Broadcom's DMU node
Message-ID: <7da2db8f-66d0-24ec-d3eb-84247b383a06 at gmail.com>
I didn't get any reply from Rob who previously pointed out that
compatible = "syscon", "simple-mfd";
is not a valid compatibility.
I suggest we hold on on DTS update for a moment and switch back to my
question from March on designing proper bindings.
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