[PATCH 0/4] Add a property to override the quad mode

[Hsin-Yi Wang]

On Wed, Aug 16, 2023 at 3:19 AM Krzysztof Kozlowski
<krzysztof.kozlowski at linaro.org> wrote:
>
> On 15/08/2023 19:21, Hsin-Yi Wang wrote:
> > On Tue, Aug 15, 2023 at 11:59 PM Michael Walle <michael at walle.cc> wrote:
> >>
> >> Hi,
> >>
> >>> On gigadevice gd25lq64c, the quad mode is enabled after BFPT is parsed.
> >>> According to datasheet[1], Quad enable (QE) bit needs to be set to 0 to
> >>> use write protection (WP) pin. It also recommends setting default value of
> >>> QE to 0 to avoid a potential short issue.
> >>
> >> So you are using either dual or single io mode. Why can't you use the device tree property spi-{tx,rx}-bus-width?
> >
> > I tried setting spi-tx-bus-width and spi-rx-bus-width to either 0 or 1
> > and WP still doesn't work.
> > For this chip, quad_enable will be set to spi_nor_sr2_bit1_quad_enable
> > (QER flag is BFPT_DWORD15_QER_SR2_BIT1_BUGGY)[1]
> >
> > spi_nor_write_sr_and_check() calls
> > spi_nor_write_16bit_sr_and_check()[2] and the function sets QE bit if
> > quad_enable is not NULL.
> >
> > [1] https://elixir.bootlin.com/linux/latest/source/drivers/mtd/spi-nor/sfdp.c#L575
> > [2] https://elixir.bootlin.com/linux/latest/source/drivers/mtd/spi-nor/core.c#L879
> >
> > Setting spi-{tx,rx}-bus-width still falls to this function and cases.
>
> with tx/rx bus width = 2, how quad mode is still possible? IOW, why do
> you need new property? You wrote here about driver, but I ask about
> bindings.
>
This may be a bug in the driver that setting spi-{tx,rx}-bus-width
still enables the QE bit. I proposed another method in the chip's
fixup to deal with this issue instead of creating a new binding
property.
v2: https://lore.kernel.org/lkml/20230816104245.2676965-1-hsinyi@chromium.org/


> Best regards,
> Krzysztof
>