Re: [PATCH v1 12/30] dt-bindings: reset: Add starfive,jh7110-reset bindings

From: Krzysztof Kozlowski
Date: Tue Oct 11 2022 - 12:38:31 EST

On 11/10/2022 11:30, Hal Feng wrote:
> On Thu, 29 Sep 2022 13:43:49 -0500, Rob Herring wrote:
>> On Fri, Sep 30, 2022 at 01:51:47AM +0800, Hal Feng wrote:
>>> Add bindings for the reset controller on the JH7110 RISC-V
>>> SoC by StarFive Technology Ltd.
>>>
>>> Signed-off-by: Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>
>>> ---
>>> .../bindings/reset/starfive,jh7110-reset.yaml | 54 +++++++++++++++++++
>>> 1 file changed, 54 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml b/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
>>> new file mode 100644
>>> index 000000000000..bb0010c200f9
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/reset/starfive,jh7110-reset.yaml
>>> @@ -0,0 +1,54 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/reset/starfive,jh7110-reset.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: StarFive JH7110 SoC Reset Controller Device Tree Bindings
>>> +
>>> +maintainers:
>>> + - Emil Renner Berthing <kernel@xxxxxxxx>
>>> + - Hal Feng <hal.feng@xxxxxxxxxxxxxxxxxxxxxx>
>>> +
>>> +properties:
>>> + compatible:
>>> + enum:
>>> + - starfive,jh7110-reset
>>
>> 'reg' needed? Is this a sub-block of something else?
>
> Yes, the reset node is a child node of the syscon node, see patch 27 for detail.
> You might not see the complete patches at that time due to technical issue of
> our smtp email server. Again, I feel so sorry about that.
>
> syscrg: syscrg@13020000 {
> compatible = "syscon", "simple-mfd";
> reg = <0x0 0x13020000 0x0 0x10000>;
>
> syscrg_clk: clock-controller@13020000 {
> compatible = "starfive,jh7110-clkgen-sys";
> clocks = <&osc>, <&gmac1_rmii_refin>,
> <&gmac1_rgmii_rxin>,
> <&i2stx_bclk_ext>, <&i2stx_lrck_ext>,
> <&i2srx_bclk_ext>, <&i2srx_lrck_ext>,
> <&tdm_ext>, <&mclk_ext>;
> clock-names = "osc", "gmac1_rmii_refin",
> "gmac1_rgmii_rxin",
> "i2stx_bclk_ext", "i2stx_lrck_ext",
> "i2srx_bclk_ext", "i2srx_lrck_ext",
> "tdm_ext", "mclk_ext";
> #clock-cells = <1>;
> };
>
> syscrg_rst: reset-controller@13020000 {
> compatible = "starfive,jh7110-reset";
> #reset-cells = <1>;

So the answer to the "reg needed?" is what? You have unit address but no
reg, so this is not correct.

> starfive,assert-offset = <0x2F8>;
> starfive,status-offset= <0x308>;
> starfive,nr-resets = <JH7110_SYSRST_END>;
> };
> };
>
> In this case, we get the memory mapped space through the parent node with syscon
> APIs. You can see patch 13 for detail.
>
> static int reset_starfive_register(struct platform_device *pdev, const u32 *asserted)
> {


(...)

>
>>
>>> +
>>> + "#reset-cells":
>>> + const: 1
>>> +
>>> + starfive,assert-offset:
>>> + description: Offset of the first ASSERT register
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>> +
>>> + starfive,status-offset:
>>> + description: Offset of the first STATUS register
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>
>> These can't be implied from the compatible string?
>
> These two properties are the key differences among different reset controllers.

Different as in different compatibles? Please answer the questions...

> There are five memory regions for clock and reset in StarFive JH7110 SoC. They
> are "syscrg", "aoncrg", "stgcrg", "ispcrg" and "voutcrg". Each memory region
> has different reset ASSERT/STATUS register offset and different number of reset
> signals.

Then these are not exactly the same devices, so using one compatible for
them does not look correct.

> After storing them in dt, the reset driver can register all reset
> controllers with the same compatible string.

Which is not how the compatible should be used...

> All we expect is that all reset
> controllers in a single SoC use the same compatible string for matching and the
> reset driver can be applied to all StarFive SoCs using different compatible strings.

Keep driver out of the talks.

> Just like

Existing bad pattern is not an argument to keep it going. Fix bad
patterns instead.

>
> arch/riscv/boot/dts/starfive/jh7100.dtsi:
>
> rstgen: reset-controller@11840000 {
> compatible = "starfive,jh7100-reset";
> reg = <0x0 0x11840000 0x0 0x10000>;
> #reset-cells = <1>;
> starfive,assert-offset = <0x0>;
> starfive,status-offset= <0x10>;
> starfive,nr-resets = <JH7100_RSTN_END>;
> };
>
> arch/riscv/boot/dts/starfive/jh7110.dtsi:
>
> syscrg: syscrg@13020000 {
> compatible = "syscon", "simple-mfd";
> reg = <0x0 0x13020000 0x0 0x10000>;
>
> syscrg_clk: clock-controller@13020000 {
> compatible = "starfive,jh7110-clkgen-sys";
> ...
> };
>
> syscrg_rst: reset-controller@13020000 {
> compatible = "starfive,jh7110-reset";
> #reset-cells = <1>;
> starfive,assert-offset = <0x2F8>;
> starfive,status-offset= <0x308>;
> starfive,nr-resets = <JH7110_SYSRST_END>;
> };
> };
>
> aoncrg: aoncrg@17000000 {
> compatible = "syscon", "simple-mfd";
> reg = <0x0 0x17000000 0x0 0x10000>;
>
> aoncrg_clk: clock-controller@17000000 {
> compatible = "starfive,jh7110-clkgen-aon";
> ...
> };
>
> aoncrg_rst: reset-controller@17000000 {
> compatible = "starfive,jh7110-reset";
> #reset-cells = <1>;
> starfive,assert-offset = <0x38>;
> starfive,status-offset= <0x3C>;
> starfive,nr-resets = <JH7110_AONRST_END>;
> };
> };
>
> stgcrg: stgcrg@10230000 { //Not submmited yet
> compatible = "syscon", "simple-mfd";
> reg = <0x0 0x10230000 0x0 0x10000>;
>
> stgcrg_clk: clock-controller@10230000 {
> compatible = "starfive,jh7110-clkgen-stg";
> ...
> };
>
> stgcrg_rst: reset-controller@10230000 {
> compatible = "starfive,jh7110-reset";
> #reset-cells = <1>;
> starfive,assert-offset = <0x74>;
> starfive,status-offset= <0x78>;
> starfive,nr-resets = <JH7110_STGRST_END>;
> };
> };
> ...
>
>>
>>> +
>>> + starfive,nr-resets:
>>> + description: Number of reset signals
>>> + $ref: /schemas/types.yaml#/definitions/uint32
>>
>> Why do you need this? Most bindings don't. If just to validate 'resets'
>> args, then don't.
>
> Can be removed. Instead, the reset driver should includes some related
> binding headers or defines some macros for pointing out the number of
> reset signals of each reset controller.
>
> Best regards,
> Hal
>
>>
>>
>>> +
>>> +required:
>>> + - compatible
>>> + - "#reset-cells"
>>> + - starfive,assert-offset
>>> + - starfive,status-offset
>>> + - starfive,nr-resets
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> + - |
>>> + #include <dt-bindings/reset/starfive-jh7110.h>
>>> +
>>> + syscrg_rst: reset-controller@13020000 {

Please test your patches.


Best regards,
Krzysztof