Re: [PATCH v2 0/5] mtd: spi-nor: Add support for Octal 8D-8D-8D mode

Pratyush Yadav
2020-05-06T09:40:39Z

On 05/05/20 05:31PM, masonccyang@mxic.com.tw wrote:
> Hi Pratyush,
> > > I can't apply your patches to enable xSPI Octal mode for
> > > mx25uw51245g because your patches set up Octal protocol first and
> > > then using Octal protocol to write Configuration Register 2(CFG
> > > Reg2). I think driver
> > > should write CFG Reg2 in SPI 1-1-1 mode (power on state) and make sure
> > > write CFG Reg 2 is success and then setup Octa protocol in the last.
> >
> > Register writes should work in 1S mode, because nor->reg_proto is only
> > set _after_ 8D mode is enabled (see spi_nor_octal_dtr_enable()). In
> > fact, both patch 15 and 16 in my series use register writes in 1S mode.
>
> but I didn't see driver roll back "nor->read/write_proto = 1"
> if xxx->octal_dtr_enable() return failed!

I copied what spi_nor_quad_enable() did, and made failure fatal. So if
xxx->octal_dtr_enable() fails, the probe would fail and the flash would
be unusable. You can try your hand at a fallback system where you try
all possible protocols available, but I think that should be a different
patchset.

--
Regards,
Pratyush Yadav