Re: drm: exynos: mixer: fix using usleep() in atomic context

[Seung-Woo Kim <sw0312.kim@samsung.com>]

Hello,

On 2015년 01월 22일 07:46, Tobias Jakobi wrote:
> Hello!
> 
> 
> Inki Dae wrote:
>> The use of spin lock, reg_slock, has been used for a long time and we
>> hadn't some cleanups to spin lock codes so far. The spin lock is also
>> used in here and there of mixer driver. And at least, it seems that
>> the use of spin lock isn't required in mixer_win_reset. I don't see
>> any atomic contexts in mixer module except interrupt handler.
>>
>> To Seung-Woo,
>> I know that you referred to mixer codes of v4l2 based mixer driver. So
>> was the spin lock used in origin v4l2 driver? or Is there any reason
>> that you used the spin lock?

The spinlock usage was originated from Tomasz Stanislawski's s5p-tv.

>>
>> Anyway, we will have some testing to check hdmi and mixer drivers
>> without spin lock. So we will remove or replace it with mutex if
>> needed.
>>
>> Thanks,
>> Inki Dae
> 
> So it's some weeks later and as far as I can see there has been no
> changes to the spinlock usage. Wouldn't it be better to apply this patch
> _now_ (since the use of 'usleep_range' is just plain wrong while under
> spinlock). When the spinlock setup gets cleaned up later, then we can
> always change back to 'usleep_range' again.
> 
> Any thoughts?

In s5p-tv, same patch is already applied by Tomasz, so I agree to apply
this patch also.

Best Regards,
- Seung-Woo Kim

> 
> With best wishes,
> Tobias
> 
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-- 
Seung-Woo Kim
Samsung Software R&D Center
--