[PATCH] clk: Dont return error when assigned-clocks is empty or missing

[Michal Simek]

On 8/28/23 17:50, Tom Rini wrote:
> On Mon, Aug 28, 2023 at 12:25:30PM +0200, Michal Simek wrote:
>>
>>
>> On 8/25/23 16:39, Tom Rini wrote:
>>> On Fri, Aug 25, 2023 at 09:15:09AM +0200, Michal Simek wrote:
>>>> Hi Tom,
>>>>
>>>> On 7/11/23 11:51, Ashok Reddy Soma wrote:
>>>>> There is a chance that assigned-clock-rates is given and assigned-clocks
>>>>> could be empty. Dont return error in that case, because the probe of the
>>>>> corresponding driver will not be called at all if this fails.
>>>>> Better to continue to look for it and return 0.
>>>>>
>>>>> Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma at amd.com>
>>>>> ---
>>>>>
>>>>>     drivers/clk/clk-uclass.c | 8 +++++++-
>>>>>     1 file changed, 7 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
>>>>> index dc3e9d6a26..f186fcbcdb 100644
>>>>> --- a/drivers/clk/clk-uclass.c
>>>>> +++ b/drivers/clk/clk-uclass.c
>>>>> @@ -329,7 +329,13 @@ static int clk_set_default_rates(struct udevice *dev,
>>>>>     			dev_dbg(dev,
>>>>>     				"could not get assigned clock %d (err = %d)\n",
>>>>>     				index, ret);
>>>>> -			continue;
>>>>> +			/* Skip if it is empty */
>>>>> +			if (ret == -ENOENT) {
>>>>> +				ret = 0;
>>>>> +				continue;
>>>>> +			}
>>>>> +
>>>>> +			return ret;
>>>>>     		}
>>>>>     		/* This is clk provider device trying to program itself
>>>>
>>>> What's your take on this one?  I didn't get reply from Sean.
>>>
>>> I guess, what's the validated upstream dts where this is the case?
>>>
>>
>> It was found by incorrect DT. It means I don't think there is any DT which
>> contains this issue.
>> But that being said we can extend current clock tests to cover this case.
>> Please look below.
> 
> Well, if the DT is invalid (and yes, we can't easily run the validation
> suite in U-Boot today), I'd rather go with a debug we can optimize out
> so that the next person with an invalid DT can more quickly find their
> problem and we don't work-around it instead.  Or am I missing something?

There is already dev_dbg print above. It means when user enable DEBUG it gets 
information about it.

The thing is that it just sync behavior with the linux kernel.
You can look at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clk/clk-conf.c?h=v6.5#n90

There is also one more example like this.
	clk-test4 {
		compatible = "sandbox,clk-test";
		assigned-clock-rates = <654>, <321>;
		assigned-clocks = <&clk_sandbox 1>;
	};

But if you prefer to fail in all these cases I am also fine with it.

Thanks,
Michal