Re: [PATCH] ARM: dts: Remove mau_pd node for Exynos5420

[Tushar Behera <tushar.behera@linaro.org>]

On 04/24/2014 03:36 PM, Tomasz Figa wrote:
> On 24.04.2014 11:07, Tushar Behera wrote:
>> On 04/23/2014 03:43 PM, Kukjin Kim wrote:
>>> Tushar Behera wrote:
>>>>
>>>> On 22 April 2014 13:08, Alim Akhtar <alim.akhtar@gmail.com> wrote:
>>>>> Hi Tushar
>>>>>
>>>>> On Tue, Apr 22, 2014 at 11:09 AM, Tushar Behera
>>>>> <tushar.behera@linaro.org> wrote:
>>>>>> MAU powerdomain provides clocks for Audio sub-system block. This
>>>>>> block
>>>>>> comprises of the I2S audio controller, audio DMA blocks and Audio
>>>>>> sub-system clock registers.
>>>>>>
>>>>>> Right now, there is no way to hook up power-domains with clock
>>>> providers.
>>>>>> During late boot when this power-domain gets disabled, we get
>>>>>> following
>>>>>> external abort.
>>>
>>> + Jonghwan Choi
>>>
>>> Well, this is not a perfect solution to support MAU power domain,
>>> it's true it is a problem right now though.
>>>
>>> In other words, this is just temporal fix for the problem.
>>>
>>> How about accessing clock stuff for audio sub-system with handling
>>> MAU power domain via generic IO power domain?
>>>
>>
>> + Tomasz Figa
>>
>> Existing power domain driver exynos4_pm_init_power_domain is registered
>> with an arch_initcall whereas the clk-exynos-audss driver is registered
>> with core_initcall. Hence even if add mau_pd node to clk-exynos-audss
>> node, the binding with power-domain doesn't happen.
> 
> I'd say core_initcall is way too early for clk-exynos-audss driver. It
> should be at most subsys_initcall. As far as I can see, all users of
> clocks provided by this driver (i.e. i2s) are probed at device_initcall
> level anyway.
> 

It is also used by ADMA node, which gets probed.

>>
>> Alternately, if Tomasz's patches are applied [1], power-domain binding
>> is successful. But because of the init order, clk-exynos-audss defers
>> probe resulting in a kernel crash. Forcing clk-exynos-audss to register
>> through arch_initcall() fixes this issue, but I am not sure if that is
>> okay.
> 
> If the driver crashes on deferred probe, then it's a bug and it should
> be fixed.
> 

By the time clk-exynos-audss is getting called, mau_pd is already
disabled by power-domain driver. That is not getting enabled during
clk-exynos-audss probe. Am I missing something?


> Best regards,
> Tomasz


-- 
Tushar Behera