[PATCH v4 04/10] coresight: Appropriately disable programming clocks

[Suzuki K Poulose]

On 21/07/2025 14:59, Leo Yan wrote:
> On Mon, Jul 21, 2025 at 12:40:38PM +0100, Suzuki Kuruppassery Poulose wrote:
>> On 21/07/2025 11:48, Leo Yan wrote:
>>> On Mon, Jul 21, 2025 at 10:15:22AM +0100, Suzuki Kuruppassery Poulose wrote:
>>>
>>> [...]
>>>
>>>>> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
>>>>> index 4ac65c68bbf44b98db22c3dad2d83a224ce5278e..dd2b4cc7a2b70cf060a3207548fe80e3824c489f 100644
>>>>> --- a/include/linux/coresight.h
>>>>> +++ b/include/linux/coresight.h
>>>>> @@ -480,26 +480,16 @@ static inline bool is_coresight_device(void __iomem *base)
>>>>>      * Returns:
>>>>>      *
>>>>>      * clk   - Clock is found and enabled
>>>>> - * NULL  - clock is not found
>>>>
>>>> This is still valid, right ?
>>>
>>> No. Since this patch uses devm_clk_get_enabled() to get a clock, if the
>>> pclk is not found, it returns -ENOENT (see of_parse_clkspec()).
>>>
>>> Only the optional clock APIs (e.g., devm_clk_get_optional_enabled())
>>> return a NULL pointer instead of -ENOENT when the clock is not found.
>>
>> This will break ACPI based systems, as we may not have a "pclk" described
>> for them. We should be able to tolerate "no pclk"
> 
> Get it. How about change the code like below?
> 
>    static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev)
>    {
>        struct clk *pclk;
> 
>        pclk = devm_clk_get_enabled(dev, "apb_pclk");
>        if (IS_ERR(pclk))
>            pclk = devm_clk_get_enabled(dev, "apb");
> 
>        /* Tolerate no pclk for ACPI device */
>        if ((pclk == ERR_PTR(-ENOENT)) && has_acpi_companion(dev))

That might be OK, please could you test this out ?




>            return NULL;
> 
>        return pclk;
>    }