[1/1] arm64: tegra: fix PPI interrupt flag

The interrupt flag for PPI should not be set to any value, since the
register is read-only. Fix the flags for the PPI interrupts to
IRQ_TYPE_NONE, so that there is no write to the read-only register.

Signed-off-by: Aniruddha Banerjee <aniruddhab@nvidia.com>
---
 arch/arm64/boot/dts/nvidia/tegra132.dtsi | 8 ++++----
 arch/arm64/boot/dts/nvidia/tegra186.dtsi | 8 ++++----
 arch/arm64/boot/dts/nvidia/tegra210.dtsi | 8 ++++----
 3 files changed, 12 insertions(+), 12 deletions(-)

Adding Marc ...

On 03/04/17 12:19, Aniruddha Banerjee wrote:
> The interrupt flag for PPI should not be set to any value, since the
> register is read-only. Fix the flags for the PPI interrupts to
> IRQ_TYPE_NONE, so that there is no write to the read-only register.

If the below matches the h/w default, does this really cause a problem?

Note, we will not attempt to write the type if it matches the current
programmed type.

I had thought that the in DT file, the type for the PPI should align
with the h/w default in the case where it cannot be written. However, I
guess this is not explicitly stated anywhere I have found, but at the
same time the binding doc for the arm,gic.txt does not list
"IRQ_TYPE_NONE" as an option.

Marc, what are your thoughts?

> Signed-off-by: Aniruddha Banerjee <aniruddhab@nvidia.com>
> ---
>  arch/arm64/boot/dts/nvidia/tegra132.dtsi | 8 ++++----
>  arch/arm64/boot/dts/nvidia/tegra186.dtsi | 8 ++++----
>  arch/arm64/boot/dts/nvidia/tegra210.dtsi | 8 ++++----
>  3 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/nvidia/tegra132.dtsi b/arch/arm64/boot/dts/nvidia/tegra132.dtsi
> index 3f3a46a4bd01..219fb3c6a273 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra132.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra132.dtsi
> @@ -1093,13 +1093,13 @@
>  	timer {
>  		compatible = "arm,armv7-timer";
>  		interrupts = <GIC_PPI 13
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 14
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 11
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 10
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>;
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>;
>  		interrupt-parent = <&gic>;
>  	};
>  };
> diff --git a/arch/arm64/boot/dts/nvidia/tegra186.dtsi b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
> index 62fa85ae0271..e602299f7694 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra186.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
> @@ -390,13 +390,13 @@
>  	timer {
>  		compatible = "arm,armv8-timer";
>  		interrupts = <GIC_PPI 13
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 14
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 11
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 10
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>;
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>;
>  		interrupt-parent = <&gic>;
>  	};
>  };
> diff --git a/arch/arm64/boot/dts/nvidia/tegra210.dtsi b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
> index 2f832df29da8..6f3060b40a40 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra210.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra210.dtsi
> @@ -1214,13 +1214,13 @@
>  	timer {
>  		compatible = "arm,armv8-timer";
>  		interrupts = <GIC_PPI 13
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 14
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 11
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>,
>  			     <GIC_PPI 10
> -				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>;
> +				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_NONE)>;
>  		interrupt-parent = <&gic>;
>  	};

Cheers
Jon

On 03/04/17 13:55, Jon Hunter wrote:
> Adding Marc ...
> 
> On 03/04/17 12:19, Aniruddha Banerjee wrote:
>> The interrupt flag for PPI should not be set to any value, since the
>> register is read-only. Fix the flags for the PPI interrupts to
>> IRQ_TYPE_NONE, so that there is no write to the read-only register.
> 
> If the below matches the h/w default, does this really cause a problem?
> 
> Note, we will not attempt to write the type if it matches the current
> programmed type.
> 
> I had thought that the in DT file, the type for the PPI should align
> with the h/w default in the case where it cannot be written. However, I
> guess this is not explicitly stated anywhere I have found, but at the
> same time the binding doc for the arm,gic.txt does not list
> "IRQ_TYPE_NONE" as an option.
> 
> Marc, what are your thoughts?

My immediate answer is "Why?".

As you pointed out, we don't even try to program the GICD_ICFGR1
register if what we read from it is the right thing. Also, the GICv2
spec says in 4.3.13: "For PPIs, it is IMPLEMENTATION DEFINED whether the
most significant bit of the Int_config field is programmable.".

So NONE is always wrong (because there is no such thing in the HW), and
the DT should have a setting that matches the HW even GICD_ICFGR1 is RO
(the OS may need to know how the triggering configuration anyhow).

Aniruddha: what problem are you trying to solve here? The DT you're
touching seems just fine to me...

Thanks,

	M.