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Date: Wed, 3 Jan 2024 14:40:31 +0100
From: Manuel Traut <manut@mecka.net>
To: Jonas Karlman <jonas@kwiboo.se>
Cc: =?utf-8?Q?Ond=C5=99ej?= Jirman <megi@xff.cz>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Jessica Zhang <quic_jesszhan@quicinc.com>,
	Sam Ravnborg <sam@ravnborg.org>,
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	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	Rob Herring <robh+dt@kernel.org>,
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	Conor Dooley <conor+dt@kernel.org>,
	Heiko Stuebner <heiko@sntech.de>, Sandy Huang <hjc@rock-chips.com>,
	Mark Yao <markyao0591@gmail.com>,
	Diederik de Haas <didi.debian@cknow.org>,
	Segfault <awarnecke002@hotmail.com>,
	Arnaud Ferraris <aferraris@debian.org>,
	Danct12 <danct12@riseup.net>, dri-devel@lists.freedesktop.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v3 4/4] arm64: dts: rockchip: Add devicetree for Pine64
 PineTab2
Message-ID: <ZZVjzwgANJMdHnuo@mecka.net>
References: <20240102-pinetab2-v3-0-cb1aa69f8c30@mecka.net>
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 <775vjfucu2g2s6zzeutj7f7tapx3q2geccpxvv4ppcms4hxbq7@cbrdmlu2ryzp>
 <903e9d0c-a00c-4214-9f0e-dd676b13b428@kwiboo.se>
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In-Reply-To: <903e9d0c-a00c-4214-9f0e-dd676b13b428@kwiboo.se>

Hi Jonas and Ondřej,

> >> +&sfc {
> >> +	pinctrl-names = "default";
> >> +	pinctrl-0 = <&fspi_dual_io_pins>;
> >> +	status = "okay";
> >> +	#address-cells = <1>;
> >> +	#size-cells = <0>;
> >> +
> >> +	flash@0 {
> >> +		compatible = "jedec,spi-nor";
> >> +		reg = <0>;
> >> +		spi-max-frequency = <24000000>;
> > 
> > That's a bit on the low side. The flash chip should work for all commands up to
> > 80MHz https://megous.com/dl/tmp/b428ad9b85ac4633.png and SGM3157YC6 switch
> > for the FSPI-CLK should have high enough bandwidth, too.
> 
> I agree that this is a little bit on the low side, it was a safe rate
> that I used for U-Boot. U-Boot required an exact rate of the supported
> sfc clk rates: 24, 50, 75, 100, 125 or 150 MHz.
> 
> Please also note that the SPI NOR flash chip used in PineTab2 is not a
> GigaDevice GD25LQ128E, it should be a SiliconKaiser SK25LP128, same as
> found in the Pine64 PinePhone Pro.

The schematics for v2.0 reference a GD25LQ128EWIGR. I never checked the jedec
id. How did you retrieve this information, or is it maybe a difference in v0.1
and 2.0?

> >> +		spi-rx-bus-width = <2>;
> > 
> > GD25LQ128E supports quad I/O. Maybe try 4 if it will work.
> 
> The schematic only shows fspi D0 and D1 connected, and use the D2 line
> for eMMC_RSTn, so spi-rx-bus-width = <2> should be correct.

ack

Since it is only needed for bootloader updates and environment its maybe better
to stay on the safe side?

But I can test faster frequency if you want me to do..

Regards
Manuel