eMMC standard update JESD84-B51B

eMMC standard update JESD84-B51B

[Gregory B.]

 Hi,

There was a recent change of the eMMC standard at JEDEC. The latest version
is now JESD84-B51B.
The CSD_REV has moved to value 9.
The update of the standard is essentially to redefined the manufacturing
date field in order to be able to encode year 2026 up to 2038.
More information can be found in the commits of Linux Kernel and mmc-utils
reference below.

A couple of patches are now being released in Kernel:

   -
   https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git/commit/?h=next&id=bf60037e32e963f8053c3372c438ba272b7c30c0
   -
   https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git/commit/?h=next&id=b40ebb75b7461c69ee4da1e49cc2fed309a96349


mmc-utils is also being updated:
https://git.kernel.org/pub/scm/utils/mmc/mmc-utils.git

I was wondering whether a similar update on the uboot code might be needed,
and I haven't seen any patch or ongoing discussion on the uboot side.

Best regards,
Gregory Baudet

Re: eMMC standard update JESD84-B51B

[Peng Fan]

Hi Gregory,

On Wed, Jan 28, 2026 at 09:42:35AM +0100, Gregory B. wrote:
> Hi,
>
>There was a recent change of the eMMC standard at JEDEC. The latest version
>is now JESD84-B51B.
>The CSD_REV has moved to value 9.
>The update of the standard is essentially to redefined the manufacturing
>date field in order to be able to encode year 2026 up to 2038.
>More information can be found in the commits of Linux Kernel and mmc-utils
>reference below.
>
>A couple of patches are now being released in Kernel:
>
>   -
>   https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git/commit/?h=next&id=bf60037e32e963f8053c3372c438ba272b7c30c0
>   -
>   https://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc.git/commit/?h=next&id=b40ebb75b7461c69ee4da1e49cc2fed309a96349
>
>
>mmc-utils is also being updated:
>https://git.kernel.org/pub/scm/utils/mmc/mmc-utils.git
>
>I was wondering whether a similar update on the uboot code might be needed,
>and I haven't seen any patch or ongoing discussion on the uboot side.

Thanks for the heads up, I will give a look. If you already started to
work on this, patches are welcomed.

Thanks
Peng

>
>Best regards,
>Gregory Baudet