Subject: [PATCH] clk: samsung: Fix Exynos 5420 pinctrl setup and clock disable failure due to domain being gated

From: [email-masked] (Sylwester Nawrocki)
Date: Tue, 09 Dec 2014 14:18:19 +0100

On 09/12/14 13:59, Krzysztof Kozlowski wrote:
> On pi?, 2014-12-05 at 15:15 +0100, Krzysztof Kozlowski wrote:
>> > Audio subsystem clocks are located in separate block. On Exynos 5420 if
>> > clock for this block (from main clock domain) 'mau_epll' is gated then
>> > any read or write to audss registers will block.
>> > 
>> > This kind of boot hang was observed on Arndale Octa and Peach Pi/Pit
>> > after introducing runtime PM to pl330 DMA driver. After that commit the
>> > 'mau_epll' was gated, because the "amba" clock was disabled and there
>> > were no more users of mau_epll.
>> > 
>> > The system hang on one of steps:
>> > 1. Disabling unused clocks from audss block.
>> > 2. During audss GPIO setup (just before probing i2s0 because
>> >    samsung_pinmux_setup() tried to access memory from audss block which was
>> >    gated.
>> > 
>> > Add a workaround for this by enabling the 'mau_epll' clock in probe.
>> > 
>> > Signed-off-by: Krzysztof Kozlowski <[email-masked]>
>> > ---
>> >  drivers/clk/samsung/clk-exynos-audss.c | 29 ++++++++++++++++++++++++++++-
>> >  1 file changed, 28 insertions(+), 1 deletion(-)
>
> Sorry for pinging so quick but merge window is open and it looks like
> booting Exynos542x boards will be broken (because pl330 will no longer
> hold adma clock enabled so whole audss domain will be gated).
> 
> This is a non-intrusive workaround for that issue, as wanted by
> Sylwester:
> https://lkml.org/lkml/2014/12/5/223
> 
> Any comments on this?

The patch looks OK to me, it would be good though if someone else
has confirmed it fixes the bug. I don't have any clock patches queued
at the moment. Perhaps you could apply it directly, Mike ?

>>From my side:

Acked-by: Sylwester Nawrocki <[email-masked]>

-- 
Thanks,
Sylwester