Re: [PATCH v3 4/4] arm64: dts: rockchip: Add devicetree for Pine64 PineTab2

[Jonas Karlman]

Hi Manuel and Ondřej,

On 2024-01-02 19:07, Ondřej Jirman wrote:
> Hello Manuel,

[...]

>> +
>> +&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.

> 
>> +		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.

> 
>> +		spi-tx-bus-width = <1>;
>> +	};
>> +};
>> +

Regards,
Jonas