Hi Geert,
Thanks for the feedback.
> Subject: Re: [PATCH 19/22] ARM: dts: r8a7744-iwg20m: Add SPI NOR support
>
> Hi Biju,
>
> On Fri, Nov 30, 2018 at 11:34 AM Biju Das <biju.das@xxxxxxxxxxxxxx> wrote:
> > > Subject: Re: [PATCH 19/22] ARM: dts: r8a7744-iwg20m: Add SPI NOR
> > > support On Tue, Nov 27, 2018 at 1:05 PM Biju Das
> <biju.das@xxxxxxxxxxxxxx> wrote:
> > > > Add support for the SPI NOR device used to boot up the system to
> > > > the iWave RZ/G1N Qseven System On Module DT.
> > > >
> > > > Signed-off-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > >
> > > Thanks for your patch!
> > >
> > > > --- a/arch/arm/boot/dts/r8a7744-iwg20m.dtsi
> > > > +++ b/arch/arm/boot/dts/r8a7744-iwg20m.dtsi
> > >
> > > > @@ -53,6 +58,27 @@
> > > > status = "okay";
> > > > };
> > > >
> > > > +&qspi {
> > > > + pinctrl-0 = <&qspi_pins>;
> > > > + pinctrl-names = "default";
> > > > +
> > > > + status = "okay";
> > > > +
> > > > + /* WARNING - This device contains the bootloader. Handle with
> care.
> > > */
> > > > + flash: flash@0 {
> > > > + #address-cells = <1>;
> > > > + #size-cells = <1>;
> > > > + compatible = "sst,sst25vf016b", "jedec,spi-nor";
> > >
> > > According to the schematics, this is an ISSI IS25LP016D?
> > > ISSI was acquired by GigaDevice, according to Wikipedia.
> > > While SST is now MicroChip.
> >
> > As per the schematic and BoM, it is.
> > IC FLASH 16MBIT 50MHZ 8SOIC SST25VF016B-50-4I-S2AF Microchip
> > Technology 1 U1
>
> Oh, this seems to differ for different revisions of the schematics.
> R5.1 has the ISSI part, R3.4 has the SST part.
>
> Due to "jedec,spi-nor", it will auto-detect, but IIRC, the driver will warn if the
> compatible doesn't match the detected part, which thus may happen for
> some boards.
OK. Will remove "sst" part for the compatible string.
> > > > + reg = <0>;
> > > > + spi-max-frequency = <50000000>;
> > > > + spi-tx-bus-width = <1>;
> > > > + spi-rx-bus-width = <1>;
> > >
> > > <1> is the default, but it's indeed good to make this explicit, as
> > > this is a QSPI device with 2 unwired data pins.
> > > However, as the device seems to support dual transfers, and dual
> > > mode uses the standard MOSI/MISO pins, you should use <2> for both.
> > > The RSPI driver supports this.
> > >
> > > The same applies to the RZ/G1M version.
> >
> > SST25VF016B this doesn't support dual mode.
>
> OK.
>
> So some boards have a dual-capable part, others don't.
>
> I'm not 100% sure, but I think writing <2> will still work, as the driver won't
> use dual mode on the SST25VF016B part, due to lack of
> SPI_NOR_DUAL_READ in the entry in the spi-nor driver.
OK. Will check this.
Regards,
Biju
Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
