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Date:   Tue, 8 Mar 2022 12:41:11 +0100
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Andrew Lunn <andrew@lunn.ch>,
        Gregory Clement <gregory.clement@bootlin.com>,
        Marek =?utf-8?B?QmVow7pu?= <kabel@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arm64: dts: marvell: armada-37xx: Remap IO space to
 bus address 0x0
Message-ID: <20220308114111.lxqika2l4scw2pk5@pali>
References: <20220218212526.16021-1-pali@kernel.org>
 <20220304163027.29357-1-pali@kernel.org>
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Hello! Could you review this change?

On Friday 04 March 2022 17:30:27 Pali Rohár wrote:
> Legacy and old PCI I/O based cards do not support 32-bit I/O addressing.
> 
> Since commit 64f160e19e92 ("PCI: aardvark: Configure PCIe resources from
> 'ranges' DT property") kernel can set different PCIe address on CPU and
> different on the bus for the one A37xx address mapping without any firmware
> support in case the bus address does not conflict with other A37xx mapping.
> 
> So remap I/O space to the bus address 0x0 to enable support for old legacy
> I/O port based cards which have hardcoded I/O ports in low address space.
> 
> Note that DDR on A37xx is mapped to bus address 0x0. And mapping of I/O
> space can be set to address 0x0 too because MEM space and I/O space are
> separate and so do not conflict.
> 
> Remapping IO space on Turris Mox to different address is not possible to
> due bootloader bug.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 76f6386b25cc ("arm64: dts: marvell: Add Aardvark PCIe support for Armada 3700")
> Cc: stable@vger.kernel.org # 64f160e19e92 ("PCI: aardvark: Configure PCIe resources from 'ranges' DT property")
> Cc: stable@vger.kernel.org # 514ef1e62d65 ("arm64: dts: marvell: armada-37xx: Extend PCIe MEM space")
> Cc: stable@vger.kernel.org # ???????????? ("arm64: dts: marvell: armada-37xx: Increase PCIe IO size from 64 KiB to 1 MiB")
> 
> ---
> Changes in v2:
> * Do not remap IO space on Turris Mox
> ---
>  arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts | 7 ++++++-
>  arch/arm64/boot/dts/marvell/armada-37xx.dtsi           | 2 +-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> index 6581092c2c90..2838e3f65ada 100644
> --- a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> +++ b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> @@ -150,17 +150,22 @@
>  	slot-power-limit = <10000>;
>  	/*
>  	 * U-Boot port for Turris Mox has a bug which always expects that "ranges" DT property
>  	 * contains exactly 2 ranges with 3 (child) address cells, 2 (parent) address cells and
> -	 * 2 size cells and also expects that the second range starts at 16 MB offset. If these
> +	 * 2 size cells and also expects that the second range starts at 16 MB offset. Also it
> +	 * expects that first range uses same address for PCI (child) and CPU (parent) cells (so
> +	 * no remapping) and that this address is the lowest from all specified ranges. If these
>  	 * conditions are not met then U-Boot crashes during loading kernel DTB file. PCIe address
>  	 * space is 128 MB long, so the best split between MEM and IO is to use fixed 16 MB window
>  	 * for IO and the rest 112 MB (64+32+16) for MEM. Controller supports 32-bit IO mapping.
>  	 * This bug is not present in U-Boot ports for other Armada 3700 devices and is fixed in
>  	 * U-Boot version 2021.07. See relevant U-Boot commits (the last one contains fix):
>  	 * https://source.denx.de/u-boot/u-boot/-/commit/cb2ddb291ee6fcbddd6d8f4ff49089dfe580f5d7
>  	 * https://source.denx.de/u-boot/u-boot/-/commit/c64ac3b3185aeb3846297ad7391fc6df8ecd73bf
>  	 * https://source.denx.de/u-boot/u-boot/-/commit/4a82fca8e330157081fc132a591ebd99ba02ee33
> +	 * Bug related to requirement of same child and parent addresses for first range is fixed
> +	 * in U-Boot version 2022.04 by following commit:
> +	 * https://source.denx.de/u-boot/u-boot/-/commit/1fd54253bca7d43d046bba4853fe5fafd034bc17
>  	 */
>  	#address-cells = <3>;
>  	#size-cells = <2>;
>  	ranges = <0x81000000 0 0xe8000000   0 0xe8000000   0 0x01000000   /* Port 0 IO */
> diff --git a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> index 549c3f7c5b27..a099b7787429 100644
> --- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> +++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> @@ -514,9 +514,9 @@
>  			 * IO at the end and the remaining seven windows
>  			 * (totaling 127 MiB) for MEM.
>  			 */
>  			ranges = <0x82000000 0 0xe8000000   0 0xe8000000   0 0x07f00000   /* Port 0 MEM */
> -				  0x81000000 0 0xeff00000   0 0xeff00000   0 0x00100000>; /* Port 0 IO*/
> +				  0x81000000 0 0x00000000   0 0xeff00000   0 0x00100000>; /* Port 0 IO */
>  			interrupt-map-mask = <0 0 0 7>;
>  			interrupt-map = <0 0 0 1 &pcie_intc 0>,
>  					<0 0 0 2 &pcie_intc 1>,
>  					<0 0 0 3 &pcie_intc 2>,
> -- 
> 2.20.1
>