[PATCH v2 01/30] mtd: spi-nor: Add config to enable flash DTR

[Jagan Teki]

On Sun, Dec 31, 2023 at 11:27 PM Bhumkar, Tejas Arvind
<tejas.arvind.bhumkar at amd.com> wrote:
>
> [AMD Official Use Only - General]
>
> Hi Jagan,
>
> > -----Original Message-----
> > From: Jagan Teki <jagan at amarulasolutions.com>
> > Sent: Wednesday, December 20, 2023 1:00 PM
> > To: Bhumkar, Tejas Arvind <tejas.arvind.bhumkar at amd.com>
> > Cc: u-boot at lists.denx.de; joe.hershberger at ni.com; rfried.dev at gmail.com;
> > Simek, Michal <michal.simek at amd.com>; vigneshr at ti.com; git at xilinx.com; T
> > Karthik Reddy <t.karthik.reddy at amd.com>
> > Subject: Re: [PATCH v2 01/30] mtd: spi-nor: Add config to enable flash DTR
> >
> > Caution: This message originated from an External Source. Use proper caution
> > when opening attachments, clicking links, or responding.
> >
> >
> > On Wed, Dec 6, 2023 at 3:02 PM Tejas Bhumkar
> > <tejas.arvind.bhumkar at amd.com> wrote:
> > >
> > > From: T Karthik Reddy <t.karthik.reddy at amd.com>
> > >
> > > The spi-nor framework will set up the flash parameters by reading the
> > > flash id table flags, which include cmd opcodes, address width, dummy
> > > bytes, and bus width. In case, flash supports octal DTR mode and the
> > > controller does not support the DTR. There is no process to switch
> > > back to SDR mode.
> > > To avoid this issue, create a Kconfig option SPI_FLASH_DTR_ENABLE to
> > > explicitly specify to enable/disable flash DTR support.
> > > This config is disabled by default.
> >
> > We cannot control controller fixup in flash, DTR read based on the DTR flag I don't
> > think adding extra CONFIG to hack the controller with impact is.
> [Tejas] : By default, this configuration is set to Disabled. It serves as a convenient option for operating the flash
>         between SDR and DDR without requiring any adjustments to the nor-id table flags.

This look like controller hack to me, may be a clear negotiation b/w
controller and flag might have proper solution.

Jagan.