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

[Suzuki K Poulose <suzuki.poulose@arm.com>]

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"

Suzuki


> 
> Thanks,
> Leo