Re: [PATCH v3] nvmem: u-boot-env: align endianness of crc32 values

[Christian Lamparter]

On 2/13/23 14:37, Rafał Miłecki wrote:
> On 2023-02-13 14:23, INAGAKI Hiroshi wrote:
> > This patch fixes crc32 error on Big-Endianness system by conversion of
> > calculated crc32 value.
> >
> > Little-Endianness system:
> >
> >   obtained crc32: Little
> > calculated crc32: Little
> >
> > Big-Endianness system:
> >
> >   obtained crc32: Little
> > calculated crc32: Big
> >
> > log (APRESIA ApresiaLightGS120GT-SS, RTL8382M, Big-Endianness):
> >
> > [    8.570000] u_boot_env
> > 18001200.spi:flash@0:partitions:partition@c0000: Invalid calculated
> > CRC32: 0x88cd6f09 (expected: 0x096fcd88)
> > [    8.580000] u_boot_env: probe of
> > 18001200.spi:flash@0:partitions:partition@c0000 failed with error -22
> >
> > Fixes: f955dc144506 ("nvmem: add driver handling U-Boot environment variables")
> >
> > Signed-off-by: INAGAKI Hiroshi <musashino.open@xxxxxxxxx>
> > ---
> > v2 -> v3
> >
> > - fix sparse warning by using __le32 type and cpu_to_le32
> > - fix character length of the short commit hash in "Fixes:" tag
> >
> > v1 -> v2
> >
> > - wrong fix for sparse warning due to misunderstanding
> > - add missing "Fixes:" tag
> >
> >  drivers/nvmem/u-boot-env.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
> > index 29b1d87a3c51..164bb04dfc3b 100644
> > --- a/drivers/nvmem/u-boot-env.c
> > +++ b/drivers/nvmem/u-boot-env.c
> > @@ -117,8 +117,8 @@ static int u_boot_env_parse(struct u_boot_env *priv)
> >      size_t crc32_offset;
> >      size_t data_offset;
> >      size_t data_len;
> > -    uint32_t crc32;
> > -    uint32_t calc;
> > +    __le32 crc32;
> > +    __le32 calc;
> >      size_t bytes;
> >      uint8_t *buf;
> >      int err;
>
> This looks counter-intuitive to me, to store values on host system in
> specified endianness. I'd say we should use __le32 type only to
> represent numbers in device stored data (e.g. structs as processed by
> device).
>
> My suggesion: leave uint32_t for local variables and use le32_to_cpu().

Hmm, this is strange. The kernel's u-boot-env driver works without any
additional changes in the le<->be department on the Big-Endian
PowerPC APM82181 WD MyBook Live NAS.

Is there something odd going on with the WD MyBook Live, or is it
the APRESIA ApresiaLightGS120GT-SS that is special?

Regards,
Christian