Re: [PATCH 1/3] clk: ignore of_device_ensure_probed error in clock lookup

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 17.01.22 11:20, Ahmad Fatoum wrote:
> On 17.01.22 10:16, Lucas Stach wrote:
>> Hi Ahmad,
>>
>> Am Montag, dem 17.01.2022 um 06:12 +0100 schrieb Ahmad Fatoum:
>>> Hello Lucas,
>>>
>>> On 16.01.22 22:32, Lucas Stach wrote:
>>>> For CLK_OF_DECLARE clocks there is no driver that is bound to the device,
>>>> so the lookup fails before even trying to find the provider, breaking
>>>> the parent_ready() logic used when initializing the declared providers.
>>>>
>>>> Ignore the return code from of_device_ensure_probed to allow the lookup
>>>> to proceed as usual. If of_device_ensure_probed the lookup will also fail,
>>>> as no provider will be found.
>>>
>>> This seems to be an alternate fix for the issue addressed by:
>>> bd516e38dd14 ("clk: handle CLK_OF_DECLARE in deep probe")
>>>
>>> What do you think?
>>
>> Yes, it seems to be aimed at the same issue. However, your fix in
>> bd516e38dd14 doesn't fix my specific issue, as we still don't get the
>> correct -EPROBE_DEFER error code for the logic in parent_ready() in
>> drivers/clk/clk.c to work.
>>
>> I guess we could even revert your fix if we agree that ignoring the
>> return code here is the right thing to do? Attaching a dummy driver 
>> doesn't seem to be totally correct, as I think it isn't prohibited to
>> have both a CLK_OF_DECLARE clock controller and a real platform driver
>> for other uses attached to the same OF node. While I'm not aware of any
>> clock controllers where this would be the case, I have seen such
>> constructs with IRQ controllers.
> 
> Sounds logical. I'll test with my fix reverted and yours applied
> and report back.

Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

"clk: handle CLK_OF_DECLARE in deep probe" can be dropped again.

> 
>>
>> Regards,
>> Lucas
>>
>>>
>>>>
>>>> Signed-off-by: Lucas Stach <dev@lynxeye.de>
>>>> ---
>>>>  drivers/clk/clk.c | 6 ++----
>>>>  1 file changed, 2 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>>>> index 189c9c62df5c..a1d1d7f1a467 100644
>>>> --- a/drivers/clk/clk.c
>>>> +++ b/drivers/clk/clk.c
>>>> @@ -643,11 +643,9 @@ struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
>>>>  {
>>>>  	struct of_clk_provider *provider;
>>>>  	struct clk *clk = ERR_PTR(-EPROBE_DEFER);
>>>> -	int ret;
>>>>  
>>>> -	ret = of_device_ensure_probed(clkspec->np);
>>>> -	if (ret)
>>>> -		return ERR_PTR(ret);
>>>> +	/* Ignore error, as CLK_OF_DECLARE clocks have no proper driver. */
>>>> +	of_device_ensure_probed(clkspec->np);
>>>>  
>>>>  	/* Check if we have such a provider in our array */
>>>>  	list_for_each_entry(provider, &of_clk_providers, link) {
>>>>
>>>
>>>
>>
>>
>>
> 
> 


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