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

[Kevin Hilman]

On Wed, Dec 17, 2014 at 10:58 PM, Mike Turquette <mturquette at linaro.org> wrote:
> Quoting Mike Turquette (2014-12-17 07:23:22)
>> Quoting Krzysztof Kozlowski (2014-12-16 00:20:15)
>> > On pon, 2014-12-15 at 14:26 -0800, Kevin Hilman wrote:
>> > > Kevin Hilman <khilman at kernel.org> writes:
>> > >
>> > > > Sylwester Nawrocki <s.nawrocki at samsung.com> writes:
>> > > >
>> > > >> On 09/12/14 13:59, Krzysztof Kozlowski wrote:
>> > > >>> On pią, 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 <k.kozlowski at samsung.com>
>> > > >>>> > ---
>> > > >>>> >  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 ?
>> > > >
>> > > > I confirm it fixes the boot hang in linux-next (next-20141210) on my
>> > > > exynos5800-peach-pi and exynos5420-arndale-octa.  Tested both
>> > > > exynos_defconfig and multi_v7_defconfig.
>> > > >
>> > > > Tested-by: Kevin Hilman <khilman at linaro.org>
>> > >
>> > > What's the status of this patch?  linux-next is still broken for several
>> > > Exynos5 platforms without this fix.
>> >
>> > I believe not only next is broken but also current mainline because
>> > runtime PM for pl330 was merged yesterday...
>> >
>> > The patch received two tested-bys (Kevin's and Javier's) and Sylwester's
>> > ack.
>> >
>> > Mike, could you pick the patch and send it to Linus after rc1?
>>
>> Will do.
>
> To be clear, I pulled this into clk-next towards -rc1, so it won't need
> to go through as an -rc fix.

This hit today's linux-next, and exynos5 platforms are happily booting
again.  Thanks!

Kevin