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

[Manuel Traut <manut@mecka.net>]

Hi Jonas,

On Wed, Jan 03, 2024 at 03:19:25PM +0100, Jonas Karlman wrote:
> Hi Manuel,
> 
> On 2024-01-03 14:40, Manuel Traut wrote:
> > 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?
> 
> This was when working on mainline U-Boot for the PineTab2 (and other
> rk356x devices). See [1] for a pending U-Boot patch that is waiting on a
> proper mainline linux devicetree for the PT2.
> 
> The JEDEC ID is reported as 0x257018 on my v2.0 production unit, and
> does not match the JEDEC ID for GD25LQ128E (0xc86018) referenced in
> the schematics.
> 
> I found that the JEDEC ID 0x257018 was referenced in prior patches
> related to the SK25LP128 SPI NOR flash chip used in Pine64 PinePhone Pro.
> 
> I have only ever tested the 24 MHz rate, but I am expecting that e.g.
> 100 MHz also should work. Will not be able to test on my PT2 until at
> earliest next week.
> 
> [1] https://github.com/Kwiboo/u-boot-rockchip/commit/66562d6eaf2c11a9f97fcdba379d3ceda8aa70ef

Thanks for the information.

My v2.0 device also reports JEDEC ID 0x257018. I increased the clock-rate
to 100 MHz and it is at least still detected.

I will find out how to test more, currently hexdump /dev/mtd0 just reports
0xff on the hole flash, I expected to see u-boot there..

Regards
Manuel

> >>>> +		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
> 

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