[PATCH] ARM: dts: Remove g2d_pd node for exynos5420

[PATCH] ARM: dts: Remove g2d_pd node for exynos5420

[Arun Kumar K]

G2D power domain also controls the CMU block of G2D.
Since clock registers can be accessed anytime for viewing
clk_summary, it can cause a system crash if g2d power domain
is disabled.

Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
---
Please also refer to the existing discussion on removal of
mau_pd node.
http://comments.gmane.org/gmane.linux.kernel.samsung-soc/29718

This patch also fixes a similar issue of the power domian being
linked to the CMU block. AFAIK, only MAU and G2D power domains
has this problem in 5420.

The issue is more critical now with the merging of following
patches in Tomasz's clk tree -
clk: samsung exynos5250/5420: Add gate clock for SSS module
clk: exynos5420: update clocks for G2D and G3D blocks

With these patches, I get the following crash on kernel booting -
[8.971209] Unhandled fault: imprecise external abort (0x1406) at 0x00000000
[8.993044] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007

For fixing this, either g2d_pd has to be removed or we need to make all
GATE clocks touching the GATE_IP_G2D as CLK_IGNORE_UNUSED.
I believe removing g2d_pd is the better solution as we get almost the
same power saving by gating off these clocks and keeping the domain ON.
---
 arch/arm/boot/dts/exynos5420.dtsi |    6 ------
 1 file changed, 6 deletions(-)

diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
index 2f6da50..47d3f17 100644
--- a/arch/arm/boot/dts/exynos5420.dtsi
+++ b/arch/arm/boot/dts/exynos5420.dtsi
@@ -242,11 +242,6 @@
 		reg = <0x100440E0 0x20>;
 	};
 
-	g2d_pd: power-domain@10044100 {
-		compatible = "samsung,exynos4210-pd";
-		reg = <0x10044100 0x20>;
-	};
-
 	msc_pd: power-domain@10044120 {
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10044120 0x20>;
@@ -755,6 +750,5 @@
 		interrupts = <0 112 0>;
 		clocks = <&clock 471>;
 		clock-names = "secss";
-		samsung,power-domain = <&g2d_pd>;
 	};
 };
-- 
1.7.9.5

Re: [PATCH] ARM: dts: Remove g2d_pd node for exynos5420

[Kukjin Kim]

On 05/13/14 18:15, Arun Kumar K wrote:
> G2D power domain also controls the CMU block of G2D.
> Since clock registers can be accessed anytime for viewing
> clk_summary, it can cause a system crash if g2d power domain
> is disabled.
>
> Signed-off-by: Arun Kumar K<arun.kk@samsung.com>
> ---
> Please also refer to the existing discussion on removal of
> mau_pd node.
> http://comments.gmane.org/gmane.linux.kernel.samsung-soc/29718
>
> This patch also fixes a similar issue of the power domian being
> linked to the CMU block. AFAIK, only MAU and G2D power domains
> has this problem in 5420.
>
> The issue is more critical now with the merging of following
> patches in Tomasz's clk tree -
> clk: samsung exynos5250/5420: Add gate clock for SSS module
> clk: exynos5420: update clocks for G2D and G3D blocks
>
> With these patches, I get the following crash on kernel booting -
> [8.971209] Unhandled fault: imprecise external abort (0x1406) at 0x00000000
> [8.993044] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007
>
> For fixing this, either g2d_pd has to be removed or we need to make all
> GATE clocks touching the GATE_IP_G2D as CLK_IGNORE_UNUSED.
> I believe removing g2d_pd is the better solution as we get almost the
> same power saving by gating off these clocks and keeping the domain ON.
> ---
>   arch/arm/boot/dts/exynos5420.dtsi |    6 ------
>   1 file changed, 6 deletions(-)
>
> diff --git a/arch/arm/boot/dts/exynos5420.dtsi b/arch/arm/boot/dts/exynos5420.dtsi
> index 2f6da50..47d3f17 100644
> --- a/arch/arm/boot/dts/exynos5420.dtsi
> +++ b/arch/arm/boot/dts/exynos5420.dtsi
> @@ -242,11 +242,6 @@
>   		reg =<0x100440E0 0x20>;
>   	};
>
> -	g2d_pd: power-domain@10044100 {
> -		compatible = "samsung,exynos4210-pd";
> -		reg =<0x10044100 0x20>;
> -	};
> -
>   	msc_pd: power-domain@10044120 {
>   		compatible = "samsung,exynos4210-pd";
>   		reg =<0x10044120 0x20>;
> @@ -755,6 +750,5 @@
>   		interrupts =<0 112 0>;
>   		clocks =<&clock 471>;
>   		clock-names = "secss";
> -		samsung,power-domain =<&g2d_pd>;
>   	};
>   };

OK, applied.

Thanks,
Kukjin