[U-Boot] Regressions in MTD / SPI FLASH

[Schrempf Frieder]

Hi Eugeniy,

On 04.09.19 20:07, Eugeniy Paltsev wrote:
> We faced with regressions caused by
> commit c4e8862308d4 (mtd: spi: Switch to new SPI NOR framework)
> This switch was performed by removing entire u-boot spi-flash
> core implementation and copying it from another project.
> However the switch is performed without proper testing and
> investigations about fixes/improvements were made in u-boot
> spi-flash core. This results in regressions.
> 
> One of regression we faced with is related to SST26 flash series which
> is used on HSDK board. The cause is that SST26 protection ops
> implementation was dropped. The fix of this regression is send
> as a patch in this series.
> 
> However there are another regressions. I.E: we also faced with broken
> SPI flash on another SNPS boards - AXS101 and AXS103. They use different
> flash IC (n25q512ax3) and I didn't investigate the cause yet.
> 
> I can also expect regressions among other u-boot users
> and I believe that subsystem changes mustn't be done such harmful way.

Actually such changes are only as much "harmful" as they are not tested 
on all of the hardware and this depends only on how many developers with 
specific boards step up to test these changes.

As Vignesh already explained, syncing the framework from Linux to U-Boot 
was desperately needed and I'm very glad, that he did the work. 
Otherwise we would still be stuck with rather old and unmaintainable 
code, that would even cause more issues in the long term.

Regards
Frieder

> 
> Eugeniy Paltsev (1):
>    MTD: SPI: revert removing SST26* flash IC protection ops
> 
>   drivers/mtd/spi/sf_internal.h  |   1 +
>   drivers/mtd/spi/spi-nor-core.c | 181 +++++++++++++++++++++++++++++++++
>   drivers/mtd/spi/spi-nor-ids.c  |   8 +-
>   include/linux/mtd/spi-nor.h    |   4 +
>   4 files changed, 190 insertions(+), 4 deletions(-)
>