[U-Boot] [PATCH 0/3] Read SFDP parameters and access flash above 16MB

[Simon Goldschmidt]

On Wed, Oct 31, 2018 at 10:38 AM Rajat Srivastava
<rajat.srivastava at nxp.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
> > Sent: Wednesday, October 31, 2018 1:09 PM
> > To: Rajat Srivastava <rajat.srivastava at nxp.com>; U-Boot Mailing List <u-
> > boot at lists.denx.de>
> > Cc: Jagan Teki <jagan at openedev.com>
> > Subject: Re: [U-Boot] [PATCH 0/3] Read SFDP parameters and access flash
> > above 16MB
> >
> > On Tue, Oct 30, 2018 at 9:35 PM Simon Goldschmidt
> > <simon.k.r.goldschmidt at gmail.com> wrote:
> > >
> > > On 17.10.2018 13:27, Rajat Srivastava wrote:
> > > > Add functionality to read and parse SFDP parameters to auto-detect
> > > > flash size, page size and address width of flash. This enables
> > > > flash access above 16MB using 4-byte addressing mode.
> > > >
> > > > Add driver support to get SFDP information of flash and use it to
> > > > access flash above 16MB.
> > > >
> > > > Enable reading and parsing of SFDP parameters for Spansion's
> > > > s25fs512 flash to auto-detect its size, its page size and the
> > > > addressing mode it supports.
> > >
> > > Why do you need driver-specific code to read the sfdp parameters?
> > > Wouldn't it be much cleaner to solve this from spi_flash.c only?
> > >
> > > If so, just adding the 'spi_flash_parse_sfdp()' function on top of
> > > Stefan's patch should work?
> > >
> > > I tried testing this patch, but just like for Stefan, but it just didn't
> > > work for me and I failed to see some simple steps to adjust my spi
> > > driver to make it work.
> >
> > And taking this further, would it make sense to add a config option
> > that dumps the whole flash chip table and only uses SFDP? Then we
> > could save a lot of space in SPL for boards where reading SFDP is
> > enough.
>
> Does the whole flash chip table mean the table that consists CFI information
> as well as SFDP information? If that's so, could you please elaborate where
> would we dump and save this table? And how will this help in saving space in SPL?

I meant the 'spi_flash_ids' table in spi_flash_ids.c. This table is >
1 kByte for my configuration and it contains strings that add up to
roughly another kByte. So if we could remove this, we could save 2
kByte of unused rodata in SPL (for my SPL, rodata and rwdata are in
the same RAM).

I haven't looked into this in detail, so I don't know if this is
really possible. Just from looking at the table, it seems SFDP should
provide all the information contained therein?

Simon

>
> Rajat
>
> >
> > Simon
> >
> > >
> > > Simon
> > >
> > > >
> > > > Rajat Srivastava (3):
> > > >    mtd/spi: Add JEDEC SFDP support in SPI framework
> > > >    fsl_qspi: Access flash above 16MB using SFDP
> > > >    spi_flash_ids: Enable SFDP parsing for s25fs512 flash
> > > >
> > > >   drivers/mtd/spi/sf_internal.h   |   4 +
> > > >   drivers/mtd/spi/spi_flash.c     | 297
> > +++++++++++++++++++++++++++++++++++++---
> > > >   drivers/mtd/spi/spi_flash_ids.c |   3 +-
> > > >   drivers/spi/fsl_qspi.c          | 103 +++++++++++++-
> > > >   include/spi.h                   |   2 +
> > > >   include/spi_flash.h             | 120 ++++++++++++++++
> > > >   6 files changed, 501 insertions(+), 28 deletions(-)
> > > >
> > >