Re: [PATCH 0/2] ARM: dts: Fix imprecise external abort error when accessing Exynos MFC

[Javier Martinez Canillas]

Hello Marek,

On 05/25/2016 02:51 AM, Marek Szyprowski wrote:
> Hello,
> 
> 
> On 2016-05-24 19:41, Javier Martinez Canillas wrote:
>> This series fixes an imprecise external abort error when accessing the
>> Exynos MFC registers due the power domain configuration requiring the
>> aclk333 clock to be enabled during a domain switch.
>>
>> There isn't a dependency between the clock and Linux Samsung SoC trees
>> because the CLK_ACLK333 clock ID is already defined so the patches can
>> be picked indepedently by the relevant subsystem maintainers.
> 
> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> 
> I'm really curious what kind of async-bridge is there, but this patch
> really fixes the problem with mfc power domain.
>

Yes, the Exynos manual is not that clear about what clocks have to remain
enabled during a power domain switch for an IP block so maybe I got wrong.

I see that the MFC block has an async-bridge in "Figure 15-1" at section 
"15.2.1 NoC Probes in 5420 Bus". And I thought that since the IP block
has an async-bridge, the clock needs to remain ungated when the PMU turn
it on and off on a power domain switch.

I chose that clock because "Figure 7-10 MFC Clock Diagram" at section
"7.4.7 MFC Clock Diagram" shows that ACLK_333 is associated with the
MFC internal buses, or at least that's my understanding.

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America