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

From: E Shattow <e@freeshell.de>
To: Conor Dooley <conor@kernel.org>,
	Emil Renner Berthing <kernel@esmil.dk>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>
Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-riscv@lists.infradead.org, E Shattow <e@freeshell.de>,
	Hal Feng <hal.feng@starfivetech.com>
Subject: [PATCH v3 2/4] riscv: dts: starfive: jh7110-common: qspi flash setting read-delay 2 cycles max 100MHz
Date: Fri,  2 May 2025 03:30:42 -0700	[thread overview]
Message-ID: <20250502103101.957016-3-e@freeshell.de> (raw)
In-Reply-To: <20250502103101.957016-1-e@freeshell.de>

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@freeshell.de>
Reviewed-by: Hal Feng <hal.feng@starfivetech.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


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