Re: [PATCH v4 9/9] drm/exynos: add support for 'hdmi' clock

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Hello,

On 2015-01-22 13:51, Javier Martinez Canillas wrote:
Hello Marek,

On 01/22/2015 01:41 PM, Marek Szyprowski wrote:
+ mixer_res->hdmi = devm_clk_get(dev, "hdmi");
You need to update the Documentation/devicetree/bindings/video/exynos_mixer.txt
DT binding docs to also mention the "hdmi" clock in the list of clocks.
Right, I've send an updated version of the patch.

Great thanks.
But as I mentioned in "[PATCH v2 0/6] Enable HDMI support on Exynos platforms"
thread, while this seems to be enough to prevent the issue on Exynos4 is not
enough on the Exynos5420/5422/5800 boards I've tested.

So I wonder if $subject is fixing the root cause or just fixing a symptom and
the cause is that the exynos_hdmi DPMS handler has to be executed before the
exynos_mixer DPMS handler for DRM_MODE_DPMS_ON like is the case for DPMS_OFF
after commit 245f98f269714 ("drm/exynos: hdmi: fix power order issue").
I'm aware of the issues with Exynos542x, I've tested it with Odroid XU3,
but I
really have no idea how to fix it. The reference manual (both for power
domain
and mixer/hdmi modules) also doesn't provide any useful information for this
case.

Yeah, I'm in the same situation. All the documentation I had access to doesn't
now explain what's happening.

Just to let you know. The problem with power domain failure to turn off is something orthogonal to 'Unhandled fault: external abort on non-linefetch' issue in drm mixer driver. It looks that even if domains reports that it failed to turn off, it somehow disabled the power, because this 'external abort' issue happens on Odroid XU3 when driver tries to access mixer registers with power domain turned off. It must be something badly broken in Exynos DRM HDMI/Mixer handling of runtime pm, because
such scenario can be easily triggered simply by running
"libdrm/modetest -M exynos -s 16@13:1920x1080".

It looks that in case of Exynos4 access to mixer registers in case of disabled power domain doesn't have such terrible results and thus the driver is somehow working well.

The issue with power on/off sequence definitely IS related to clock
configuration,
but we didn't figure out how to solve it in a generic way. This will be
handled in
Exynos HDMI and mixer drivers anyway, so the DTS part (at least for
Exynos4 SoC)
will not change.

We would really like to have HDMI support for Exynos4 merged, especially
that the
first version of the HDMI patches was posted in v3.16 times and now we
are close
to v3.20 -next merge window end...

Sorry, I didn't mean to imply that $subject should be blocked. I agree with
you that the power on/off sequence has to be fixed in the hdmi and mixer
drivers and is orthogonal to the DTS changes. That's why I also decided to
finally post my "Add HDMI support for Exynos5420 platform" [0] series too.

Thanks. I hope that both series will get merged to v3.20 what will bring more
attention to this problem.

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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