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

[Tomasz Figa <t.figa@samsung.com>]

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.

>
> 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.

Best regards,
Tomasz