linux-kernel - Re: [PATCH] dt-bindings: usb: samsung,exynos-dwc3: allow unit address in DTS

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Message-ID: <afce38b0-be90-a3b5-f181-a88ad3025bd9@linaro.org>
Date:   Thu, 26 Jan 2023 11:48:26 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: usb: samsung,exynos-dwc3: allow unit address
 in DTS

On 25/01/2023 22:13, Rob Herring wrote:
> On Wed, Jan 25, 2023 at 06:59:43PM +0100, Krzysztof Kozlowski wrote:
>> The Samsung Exynos SoC USB 3.0 DWC3 Controller is a simple wrapper of
>> actual DWC3 Controller device node.  It handles necessary Samsung
>> Exynos-specific resources (regulators, clocks), but does not have its
>> own MMIO address space.
>>
>> However neither simple-bus bindings nor dtc W=1 accept device nodes in
>> soc@ node which do not have unit address.  Therefore allow using
>> the address space of child device (actual DWC3 Controller) as the
>> wrapper's address.
> 
> The correct fix is 'ranges' should have a value. Though the whole 
> wrapper thing when there are no registers I dislike...

You mean something like this (diff against this patchset):
----------
diff --git a/arch/arm/boot/dts/exynos54xx.dtsi
b/arch/arm/boot/dts/exynos54xx.dtsi
index 08786fd9c6ea..75b6f9678672 100644
--- a/arch/arm/boot/dts/exynos54xx.dtsi
+++ b/arch/arm/boot/dts/exynos54xx.dtsi
@@ -142,16 +142,15 @@ hsi2c_7: i2c@...d0000 {
                        status = "disabled";
                };

-               usbdrd3_0: usb-wrapper@...00000 {
+               usbdrd3_0: usb-wrapper {
                        compatible = "samsung,exynos5250-dwusb3";
-                       reg = <0x12000000 0x10000>;
                        #address-cells = <1>;
                        #size-cells = <1>;
-                       ranges;
+                       ranges = <0x0 0x12000000 0x10000>;

-                       usbdrd_dwc3_0: usb@...00000 {
+                       usbdrd_dwc3_0: usb@0 {
                                compatible = "snps,dwc3";
-                               reg = <0x12000000 0x10000>;
+                               reg = <0x0 0x10000>;

---------

Unfortunately dtc W=1 is still not happy:

exynos54xx.dtsi:145.26-159.5: Warning (unit_address_vs_reg):
/soc/usb-wrapper: node has a reg or ranges property, but no unit name

neither dtbs_check is:

exynos5410-smdk5410.dtb: soc: usb-wrapper: {'compatible':
['samsung,exynos5250-dwusb3'], '#address-cells': [[1]], '#size-cells':
[[1]], 'ranges': [[0, 301989888, 65536]], 'clocks': [[5, 366]],
'clock-names': ['usbdrd30'], 'pinctrl-names': ['default'], 'pinctrl-0':
[[21, 22]], 'vdd10-supply': [[23]], 'vdd33-supply': [[23]], 'usb@0':
{'compatible': ['snps,dwc3'], 'reg': [[0, 65536]], 'interrupts': [[0,
72, 4]], 'phys': [[24, 0], [24, 1]], 'phy-names': ['usb2-phy',
'usb3-phy'], 'snps,dis_u3_susphy_quirk': True}} should not be valid
under {'type': 'object'}
	From schema:
/home/krzk/.local/lib/python3.10/site-packages/dtschema/schemas/simple-bus.yaml


Best regards,
Krzysztof