Re: [PATCH] Revert "arm64: dts: juno: add dma-ranges property"

From: Robin Murphy <robin.murphy@arm.com>
To: Sudeep Holla <sudeep.holla@arm.com>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: Rob Herring <robh+dt@kernel.org>,
	Liviu Dudau <liviu.dudau@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Subject: Re: [PATCH] Revert "arm64: dts: juno: add dma-ranges property"
Date: Thu, 28 Nov 2019 15:58:28 +0000	[thread overview]
Message-ID: <1e0ad966-031a-1343-a83e-8536a678341c@arm.com> (raw)
In-Reply-To: <20191128154242.1035-1-sudeep.holla@arm.com>

On 28/11/2019 3:42 pm, Sudeep Holla wrote:
> This reverts commit 193d00a2b35ee3353813b4006a18131122087205.
> 
> Commit 951d48855d86 ("of: Make of_dma_get_range() work on bus nodes")
> reworked the logic such that of_dma_get_range() works correctly
> starting from a bus node containing "dma-ranges".
> 
> Since on Juno we don't have a SoC level bus node and "dma-ranges" is
> present only in the root node, we get the following error:
> 
> OF: translation of DMA address(0) to CPU address failed node(/sram@2e000000)
> OF: translation of DMA address(0) to CPU address failed node(/uart@7ff80000)
> ...
> OF: translation of DMA address(0) to CPU address failed node(/mhu@2b1f0000)
> OF: translation of DMA address(0) to CPU address failed node(/iommu@2b600000)
> OF: translation of DMA address(0) to CPU address failed node(/iommu@2b600000)
> OF: translation of DMA address(0) to CPU address failed node(/iommu@2b600000)
> 
> So let's fix it by dropping the "dma-ranges" property for now. We can
> add it later with a proper SoC bus node and moving all the devices that
> belong there along with the "dma-ranges" if required.

Acked-by: Robin Murphy <robin.murphy@arm.com>

As mentioned before, this is fine since it doesn't represent any kind of 
device-visible restriction; it was only there for completeness, and 
we've since given in to the assumption that missing "dma-ranges" implies 
a 1:1 mapping anyway.

Thanks,
Robin.

> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Liviu Dudau <liviu.dudau@arm.com>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>   arch/arm64/boot/dts/arm/juno-base.dtsi | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/arm/juno-base.dtsi b/arch/arm64/boot/dts/arm/juno-base.dtsi
> index 9e3e8ce6adfe..1f3c80aafbd7 100644
> --- a/arch/arm64/boot/dts/arm/juno-base.dtsi
> +++ b/arch/arm64/boot/dts/arm/juno-base.dtsi
> @@ -6,7 +6,6 @@
>   	/*
>   	 *  Devices shared by all Juno boards
>   	 */
> -	dma-ranges = <0 0 0 0 0x100 0>;
>   
>   	memtimer: timer@2a810000 {
>   		compatible = "arm,armv7-timer-mem";
> 