linux-kernel - Re: [PATCH v3 2/4] riscv: dts: starfive: jh7110-common: qspi flash setting read-delay 2 cycles max 100MHz

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Message-ID: <CAJM55Z-TMEn2oukQ_5XvyoQ4U-BVjt5dekVv2T3=vsQWL4CCuA@mail.gmail.com>
Date: Thu, 15 May 2025 10:09:34 -0700
From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
To: E Shattow <e@...eshell.de>, Conor Dooley <conor@...nel.org>, 
	Emil Renner Berthing <kernel@...il.dk>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, Hal Feng <hal.feng@...rfivetech.com>
Subject: Re: [PATCH v3 2/4] riscv: dts: starfive: jh7110-common: qspi flash
 setting read-delay 2 cycles max 100MHz

E Shattow wrote:
> Use qspi flash read-delay and spi-max-frequency settings compatible with
> U-Boot bootloader.
>
> Observations from testing on Pine64 Star64 hardware within U-Boot bootloader
> and read-delay=2 are spi-max-frequency less than 49.8MHz fails to write,
> corrupt data writes at 25MHz to 49.799999MHz, and valid data writes at
> 49.8MHz to 100MHz (not tested above 100MHz). No valid spi-max-frequency
> was found for 1<read-delay<=3 and corrupt data with read-delay=3.
>
> Looking around the Linux codebase it is common to see read-delay 2 cycles
> with spi-max-frequency 100MHz and testing confirms this to work in both
> U-Boot and Linux.
>
> Signed-off-by: E Shattow <e@...eshell.de>
> Reviewed-by: Hal Feng <hal.feng@...rfivetech.com>

Thanks!

Acked-by: Emil Renner Berthing <emil.renner.berthing@...onical.com>

> ---
>  arch/riscv/boot/dts/starfive/jh7110-common.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/boot/dts/starfive/jh7110-common.dtsi b/arch/riscv/boot/dts/starfive/jh7110-common.dtsi
> index f1489e9bb83e..5c525686c043 100644
> --- a/arch/riscv/boot/dts/starfive/jh7110-common.dtsi
> +++ b/arch/riscv/boot/dts/starfive/jh7110-common.dtsi
> @@ -317,8 +317,8 @@ &qspi {
>  	nor_flash: flash@0 {
>  		compatible = "jedec,spi-nor";
>  		reg = <0>;
> -		cdns,read-delay = <5>;
> -		spi-max-frequency = <12000000>;
> +		cdns,read-delay = <2>;
> +		spi-max-frequency = <100000000>;
>  		cdns,tshsl-ns = <1>;
>  		cdns,tsd2d-ns = <1>;
>  		cdns,tchsh-ns = <1>;
> --
> 2.49.0
>