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

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Message-id: <561EE6D4.6030803@samsung.com>
Date:	Thu, 15 Oct 2015 08:35:48 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	Javier Martinez Canillas <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>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] broken mixer after second resume from mem

On 14.10.2015 15:50, Tomeu Vizoso wrote:
> On 14 October 2015 at 07:55, Krzysztof Kozlowski
> <k.kozlowski@...sung.com> wrote:
>> On 13.10.2015 19:25, Tomeu Vizoso wrote:
>>> 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 am assuming you are talking about current linux-next. The actual
>> reparent happens in exynos_pd_power which would indicate the exynos pd
>> clock reparenting code. However the domains for Exynos5250 don't have
>> any clocks set up for reparenting... which actually might be the issue.
>> These clocks should be probably reparented - as it is done for other
>> platforms - look at 5420 example (they are glitch-free on both of SoCs).
>>
>> I've seen a such issues before. The problem is that after some time I
>> tend to forget the needed workaround and solution. :)
>>
>> Try with reparenting necessary clocks. On other platform for some kind
>> of similar issue the reset was required for the IP block - DECON
>> (actually the mux could not stabilize there which can be observed in one
>> of STATUS registers for mux).
>>
>> Let me know if explanation above is not detailed enough.
> 
> Thanks for the reply, I looked at downstream and saw that two clocks
> are being reparented and that seems to fix things. Will send a patch
> later today.
> 

Great! Happy to hear that!

Best regards,
Krzysztof



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