linux-kernel - Re: [PATCH 11/11] riscv: dts: starfive: jh7100: Use physical memory ranges for DMA

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Message-ID: <CAJM55Z-caGvqZXDTtbj0LknAJVgj1s5_p0SaN3kJog1950L0yg@mail.gmail.com>
Date: Mon, 4 Nov 2024 07:26:06 -0800
From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
To: Samuel Holland <samuel.holland@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	linux-riscv@...ts.infradead.org, Conor Dooley <conor@...nel.org>
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Alexandre Ghiti <alexghiti@...osinc.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, 
	Emil Renner Berthing <kernel@...il.dk>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>
Subject: Re: [PATCH 11/11] riscv: dts: starfive: jh7100: Use physical memory
 ranges for DMA

Samuel Holland wrote:
> JH7100 provides a physical memory region which is a noncached alias of
> normal cacheable DRAM. Now that Linux can apply PMAs by selecting
> between aliases of a physical memory region, any page of DRAM can be
> marked as noncached for use with DMA, and the preallocated DMA pool is
> no longer needed. This allows portable kernels to boot on JH7100 boards.
>
> Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
> ---
>
>  arch/riscv/Kconfig.errata                     | 19 ------------
>  .../boot/dts/starfive/jh7100-common.dtsi      | 30 ++++---------------
>  2 files changed, 6 insertions(+), 43 deletions(-)
>
> diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
> index 2806ed7916c7..fc2c7fb2caff 100644
> --- a/arch/riscv/Kconfig.errata
> +++ b/arch/riscv/Kconfig.errata
> @@ -53,25 +53,6 @@ config ERRATA_SIFIVE_CIP_1200
>
>  	  If you don't know what to do here, say "Y".
>
> -config ERRATA_STARFIVE_JH7100
> -	bool "StarFive JH7100 support"
> -	depends on ARCH_STARFIVE
> -	depends on !DMA_DIRECT_REMAP
> -	depends on NONPORTABLE
> -	select DMA_GLOBAL_POOL

Hi Samuel,

Thank you for working on this!

The JH7100 still need the RISCV_NONSTANDARD_CACHE_OPS from the sifive-ccache
driver for streaming DMA, so if I just remove the 3 lines above instead of the
whole ERRATE_STARFIVE_JH7110 (and enable RISCV_ISA_SVPBMT) this series works on
my Starlight board.

> -	select RISCV_DMA_NONCOHERENT
> -	select RISCV_NONSTANDARD_CACHE_OPS
> -	select SIFIVE_CCACHE
> -	default n
> -	help
> -	  The StarFive JH7100 was a test chip for the JH7110 and has
> -	  caches that are non-coherent with respect to peripheral DMAs.
> -	  It was designed before the Zicbom extension so needs non-standard
> -	  cache operations through the SiFive cache controller.
> -
> -	  Say "Y" if you want to support the BeagleV Starlight and/or
> -	  StarFive VisionFive V1 boards.
> -
>  config ERRATA_THEAD
>  	bool "T-HEAD errata"
>  	depends on RISCV_ALTERNATIVE
> diff --git a/arch/riscv/boot/dts/starfive/jh7100-common.dtsi b/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
> index ae1a6aeb0aea..34885fe40e2d 100644
> --- a/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
> +++ b/arch/riscv/boot/dts/starfive/jh7100-common.dtsi
> @@ -9,8 +9,14 @@
>  #include <dt-bindings/gpio/gpio.h>
>  #include <dt-bindings/leds/common.h>
>  #include <dt-bindings/pinctrl/pinctrl-starfive-jh7100.h>
> +#include <dt-bindings/riscv/physical-memory.h>
>
>  / {
> +	riscv,physical-memory-regions =
> +		<0x00 0x00000000 0x40 0x00000000 (PMA_RW | PMA_IO) 0x0>,
> +		<0x00 0x80000000 0x08 0x00000000 (PMA_RWXA | PMA_NONCOHERENT_MEMORY) 0x0>,
> +		<0x10 0x00000000 0x08 0x00000000 (PMA_RWX | PMA_NONCACHEABLE_MEMORY | PMR_ALIAS(1)) 0x0>;
> +

The size and placement of the DMA pool was kind of arbitrary but the above is
a feature of the SoC, so should be moved to jh7100.dtsi instead.

>  	aliases {
>  		mmc0 = &sdio0;
>  		mmc1 = &sdio1;
> @@ -42,30 +48,6 @@ led-ack {
>  		};
>  	};
>
> -	reserved-memory {
> -		#address-cells = <2>;
> -		#size-cells = <2>;
> -		ranges;
> -
> -		dma-reserved@...00000 {
> -			reg = <0x0 0xfa000000 0x0 0x1000000>;
> -			no-map;
> -		};
> -
> -		linux,dma@...a000000 {
> -			compatible = "shared-dma-pool";
> -			reg = <0x10 0x7a000000 0x0 0x1000000>;
> -			no-map;
> -			linux,dma-default;
> -		};
> -	};
> -
> -	soc {
> -		dma-ranges = <0x00 0x80000000 0x00 0x80000000 0x00 0x7a000000>,
> -			     <0x00 0xfa000000 0x10 0x7a000000 0x00 0x01000000>,
> -			     <0x00 0xfb000000 0x00 0xfb000000 0x07 0x85000000>;
> -	};
> -
>  	wifi_pwrseq: wifi-pwrseq {
>  		compatible = "mmc-pwrseq-simple";
>  		reset-gpios = <&gpio 37 GPIO_ACTIVE_LOW>;
> --
> 2.45.1
>