linux-kernel - [BUG] broken mixer after second resume from mem

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Date:	Tue, 13 Oct 2015 12:25:55 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	javier@...hile0.org, Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Daniel Stone <daniel.stone@...labora.co.uk>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	Kukjin Kim <kgene@...nel.org>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	linux-samsung-soc@...r.kernel.org
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [BUG] broken mixer after second resume from mem

Hi,

have been hunting down a bug on exynos5250-snow which caused both HDMI
and LVDS output to be broken after the second resume (with suspend to
mem, but not to idle).

What I have found is that when powering down the DISP1 power domain
while suspending for the second time, the contents of the SRC_TOP3
register change from 0x1110550 to 0x1110500. IIUIC, this means that
ACLK_200_DISP1 is reparented to XXTI.

When the CPU comes up again, that register contains 0x1110550 again, but
it's set to 0x1110500 by the code that restores clk registers when resuming:

First suspend:

exynos_pd_power: SRC_TOP3 1110550 disp1-power-domain@...440A0 - before
exynos_pd_power: SRC_TOP3 1110550 disp1-power-domain@...440A0 - after
exynos5250_clk_suspend: SRC_TOP3 1110550
exynos5250_clk_resume: SRC_TOP3 1110550 - before
exynos5250_clk_resume: SRC_TOP3 1110550 - after
exynos_pd_power: SRC_TOP3 1110550 disp1-power-domain@...440A0 - before
exynos_pd_power: SRC_TOP3 1110550 disp1-power-domain@...440A0 - after

Second suspend:

exynos_pd_power: SRC_TOP3 1110550 disp1-power-domain@...440A0 - before
exynos_pd_power: SRC_TOP3 1110500 disp1-power-domain@...440A0 - after
exynos5250_clk_suspend: SRC_TOP3 1110500
exynos5250_clk_resume: SRC_TOP3 1110550 - before
exynos5250_clk_resume: SRC_TOP3 1110500 - after
exynos_pd_power: SRC_TOP3 1110500 disp1-power-domain@...440A0 - before
exynos_pd_power: SRC_TOP3 1110500 disp1-power-domain@...440A0 - after

I have no idea of why it happens on the second suspend, and also don't
know why it doesn't happen when suspending to idle.

Any ideas?

Thanks,

Tomeu
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