linux-kernel - Re: [PATCH 1/1] ARM: dts: Make DP a consumer of DISP1 power domain on Exynos5420

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Message-ID: <554CF348.30803@kernel.org>
Date:	Sat, 09 May 2015 02:32:56 +0900
From:	Kukjin Kim <kgene@...nel.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
CC:	Kukjin Kim <kgene@...nel.org>,
	Doug Anderson <dianders@...omium.org>,
	Olof Johansson <olof@...om.net>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Kevin Hilman <khilman@...aro.org>,
	Tyler Baker <tyler.baker@...aro.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] ARM: dts: Make DP a consumer of DISP1 power domain
 on Exynos5420

On 04/13/15 05:30, Javier Martinez Canillas wrote:
> Commit ea08de16eb1b ("ARM: dts: Add DISP1 power domain for exynos5420")
> added a device node for the Exynos5420 DISP1 power domain but dit not
> make the DP controller a consumer of that power domain.
> 
> This causes an "Unhandled fault: imprecise external abort" error if the
> exynos-dp driver tries to access the DP controller registers and the PD
> was turned off. This lead to a kernel panic and a complete system hang.
> 
> Make the DP controller device node a consumer of the DISP1 power domain
> to ensure that the PD is turned on when the exynos-dp driver is probed.
> 
> Fixes: ea08de16eb1b ("ARM: dts: Add DISP1 power domain for exynos5420")
> Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> ---
> 
> Hello,
> 
> This latent bug was not exposed before since drivers for other devices
> marked as DISP1 power domain consumers were probed before exynos-dp so
> the PD was already on which made possible to access the DP registers.
> 
> But "regulator: Defer lookup of supply to regulator_get" [0] that is in
> linux-next from a couple of days now, changed the order on which the
> drivers' probes succeed so the PD was disabled during exynos-dp probe.
> 
> Exynos5420 machines with a display such as the Exynos5420 Peach Pit and
> Exynos5800 Peach Pi were failing to boot due this issue, i.e: [1].
> 
> Olof,
> 
> Could you please confirm $subject fixes the issue catched by your farm?
> 
> Krzysztof,
> 
> This patch conflicts with your Exynos5 phandle notation cleanup [2] but
> I preferred to send it on top of linux-next instead of making your series
> a dependency since it fixes a very important bug that had caused -next to
> be broken on these matchines for days now.
> 
> Thanks a lot and best regards,
> Javier
> 
> [0]: https://lkml.org/lkml/2015/3/24/1167
> [1]: http://arm-soc.lixom.net/bootlogs/next/next-20150409/pi-arm-exynos_defconfig.html
> [2]: https://lkml.org/lkml/2015/4/12/49
> 
>  arch/arm/boot/dts/exynos5420.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
> index f67b23f303c3..45317538bbae 100644
> --- a/arch/arm/boot/dts/exynos5420.dtsi
> +++ b/arch/arm/boot/dts/exynos5420.dtsi
> @@ -536,6 +536,7 @@
>  		clock-names = "dp";
>  		phys = <&dp_phy>;
>  		phy-names = "dp";
> +		power-domains = <&disp_pd>;
>  	};
>  
>  	mipi_phy: video-phy@...40714 {

Sorry for the late response. I've applied in -fixes and will be sent to
arm-soc soon. Thanks.

- Kukjin
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