[PATCH 1/7] media: aspeed: fix a kernel warning on clk control

[Jae Hyun Yoo]

On 5/9/2019 8:01 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2019-05-09 at 16:51 -0700, Jae Hyun Yoo wrote:
>> On 5/9/2019 4:19 PM, Benjamin Herrenschmidt wrote:
>>> On Thu, 2019-05-09 at 10:19 -0700, Jae Hyun Yoo wrote:
>>>>
>>>> Okay. Probably I need to add one another patch in this series to
>>>> address
>>>> what you pointed out.
>>>>
>>>> I have one question. I reviewed again all bitops in this driver
>>>> and
>>>> checked that some bitops are protected by a spinlock and some
>>>> others
>>>> are not. In this case, can I mix use atomic and non-atomic bitops
>>>> depend on each bitop's protection state by the spinlock? Or,
>>>> would it be
>>>> better to change all of them to bool in this case?
>>>
>>> No, if some aren't protected by a lock and some are, then they need
>>> to
>>> remain atomic.
>>>
>>> The question then becomes whether the unprotected ones are actually
>>> correct or just exposing more races.
>>
>> Got it. Not sure yet but I think the protected bitops could be moved
>> out
>> from the spinlock scope then all bitops could be kept as atomic.
> 
> Which is very likely to be extremely racy... (and gratuitously more
> costly) :-)

Okay then, will try to wrap all bitops using a single spinlock and
change all of them to non-atomic bitops. Is it right approach?

Thanks,
Jae

>>   I'll
>> look at and test this driver code more deeply again, and will submit
>> v2
>> soon.
>>
>> Again, thanks a lot for your review.
>>
>> Regards,
>> Jae
>