Re: [PATCH v2 0/9] 5p80: Add SFDP support

[Joel Stanley]

On Wed, 7 Oct 2020 at 01:43, Joel Stanley <joel@jms.id.au> wrote:
>
> On Wed, 2 Sep 2020 at 09:31, Cédric Le Goater <clg@kaod.org> wrote:
> >
> > Hello,
> >
> > JEDEC STANDARD JESD216 for Serial Flash Discovery Parameters (SFDP)
> > provides a mean to describe the features of a serial flash device
> > using a set of internal parameter tables. Support in Linux has been
> > added some time ago and the spi-nor driver is using it more often
> > to detect the flash settings and even flash models.
> >
> > This is the initial framework for the RDSFDP command giving access to
> > a private SFDP area under the flash.
> >
> > The patches available here :
> >
> >   https://github.com/legoater/qemu/commits/aspeed-5.2
>
> Reviewed-by: Joel Stanley <joel@jms.id.au>
> Tested-by: Joel Stanley <joel@jms.id.au>
>
> Note that these need to be rebased on master; there are some minor conflicts.
>
> These patches have proved essential in debugging a recent kernel
> regression. Thanks for adding this support Cédric.

For reference, an OpenBMC UBI based NOR image with an upstream (5.8,
5.9-rc) kernel can be used to reproduce the bug as follows:

qemu-system-arm -M witherspoon-bmc -nic user -nographic \
 -drive file=obmc-phosphor-image-witherspoon.ubi.mtd,format=raw,if=mtd \
 -kernel aspeed-g5-dev/arch/arm/boot/zImage \
 -dtb aspeed-g5-dev/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dtb \
 -append "console=ttyS4,115200n8 ubi.mtd=obmc-ubi,0,0,0
ubi.mtd=alt-obmc-ubi,0,0,4 ro rootfstype=squashfs ubi.block=0,1
root=/dev/ubiblock0_1"

The ubi.mtd can be found here[1].

This assumes you're running qemu with this series applied, and an
upstream kernel built with aspeed_g5_defconfig:

git checkout v5.8
CROSS_COMPILE="ccache arm-linux-gnueabi-" ARCH=arm make -j8
O=aspeed-g5-dev aspeed_g5_defconfig
CROSS_COMPILE="ccache arm-linux-gnueabi-" ARCH=arm make -j8 O=aspeed-g5-dev

The fix for the Linux kernel issue is on the linux-mtd list[2].
WIthout the fix, the kernel will fail to attach the UBI volume:

[    1.453224] ubi0: default fastmap pool size: 25
[    1.453370] ubi0: default fastmap WL pool size: 12
[    1.453505] ubi0: attaching mtd3
[    1.467316] ubi0 error: ubi_compare_lebs: unsupported on-flash UBI format
[    1.467902] ubi0 error: ubi_attach_mtd_dev: failed to attach mtd3, error -22

With the fix, the system will boot through to userspace.

Cheers,

Joel

[1] 
https://jenkins.openbmc.org/view/latest/job/latest-master/label=docker-builder,target=witherspoon/lastSuccessfulBuild/artifact/openbmc/build/tmp/deploy/images/witherspoon/obmc-phosphor-image-witherspoon.ubi.mtd
[2] 
https://lore.kernel.org/linux-mtd/CACPK8XceL_QHCQOhfus27rei0vwfRJAFjfL6JkVw9pwxJj2d6Q@mail.gmail.com/



>
> Cheers,
>
> Joel
>
> >
> > Thanks,
> >
> > C.
> >
> > Changes in v2:
> >
> >  - fixed dummy value
> >  - replaced  'sfdp' table by a 'sfdp_read' handler
> >  - more SFDP tables
> >  - fixed Aspeed SMC support
> >  - introduced mx25l25635f chip model for test under Linux.
> >
> > Cédric Le Goater (9):
> >   m25p80: Add basic support for the SFDP command
> >   m25p80: Add the n25q256a SFDP table
> >   m25p80: Add the mx25l25635e SFPD table
> >   m25p80: Add the mx25l25635f SFPD table
> >   m25p80: Add the mx66l1g45g SFDP table
> >   m25p80: Add the w25q256 SFPD table
> >   m25p80: Add the w25q512jv SFPD table
> >   arm/aspeed: Replace mx25l25635e chip model
> >   aspeed/smc: Add support for RDSFDP command
> >
> >  hw/block/m25p80_sfdp.h      |  27 ++++
> >  include/hw/ssi/aspeed_smc.h |   1 +
> >  hw/arm/aspeed.c             |   6 +-
> >  hw/block/m25p80.c           |  47 +++++-
> >  hw/block/m25p80_sfdp.c      | 296 ++++++++++++++++++++++++++++++++++++
> >  hw/ssi/aspeed_smc.c         |  21 ++-
> >  MAINTAINERS                 |   2 +-
> >  hw/block/meson.build        |   1 +
> >  hw/block/trace-events       |   1 +
> >  9 files changed, 385 insertions(+), 17 deletions(-)
> >  create mode 100644 hw/block/m25p80_sfdp.h
> >  create mode 100644 hw/block/m25p80_sfdp.c
> >
> > --
> > 2.25.4
> >