Re: [PATCH] clk: Add fault tolerance to of_clk_hw_onecell_get()

[Chuan Liu <chuan.liu@amlogic.com>]

Hi Stephen:

     After reviewing all CCF drivers referencing of_clk_hw_onecell_get(),
I confirmed their corresponding binding *.yaml files define
'#clock-cells' as 'const: 1'.

Therefore, the case I previously described is currently disallowed.
Please ignore this patch. Thanks.


On 8/1/2025 12:45 AM, Stephen Boyd wrote:
> [ EXTERNAL EMAIL ]
>
> Quoting Chuan Liu via B4 Relay (2025-07-31 05:39:58)
>> From: Chuan Liu <chuan.liu@amlogic.com>
>>
>> In specific cases, even a clk_provider managing only a single clock may
>> reference of_clk_hw_onecell_get() to access its member clocks, as seen
>> in implementations like clk-scmi.
>>
>> For a clk_provider with only one clock, when calling
>> of_parse_phandle_with_args(), the phandle_args->args[] members are not
>> assigned. In this case, the reference to phandle_args->args[0] in
>> of_clk_hw_onecell_get() becomes invalid. If phandle_args->args[0]
>> initially contains a non-zero value, this will trigger an error.
>>
>> Signed-off-by: Chuan Liu <chuan.liu@amlogic.com>
>> ---
>> Error conditions observed:
>>
>> scmi_clk: protocol@14 {
>>          reg = <0x14>;
>>          #clock-cells = <0>;
>> };
>>
>> phandle1: clock-controller@1 {
>>          #clock-cells = <1>;
>> }
>>
>> clock-consumer@2 {
>>          assigned-clocks = <&phandle1 1>,
>>                            <&scmi_clk>;
>>          assigned-clock-rates = <xxx>,
>>                                 <xxx>;
>> }
>>
>> Under these conditions, executing of_clk_set_defaults() triggers the
>> error: 'of_clk_hw_onecell_get: invalid index 1'.
> Please write a KUnit test.