Re: [PATCH v2 1/2] nvme: Enable FUA

[Bin Meng <bmeng.cn@gmail.com>]

On Mon, Sep 27, 2021 at 9:22 PM Jon Lin <jon.lin@rock-chips.com> wrote:
>
> Most NVME devcies maintain data in internal cache for an uncertain

typo: devices

> times, and u-boot has no method to force NVME to flush cache.
> So this patch adds FUA to avoid data loss caused by power off after data
> programming.
>
> Signed-off-by: Jon Lin <jon.lin@rock-chips.com>
> Reviewed-by: Stefan Agner <stefan@agner.ch>
> ---
>
> (no changes since v1)
>
>  drivers/nvme/nvme.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
> index f6465ea7f4..5d05cb6e9e 100644
> --- a/drivers/nvme/nvme.c
> +++ b/drivers/nvme/nvme.c
> @@ -761,6 +761,9 @@ static ulong nvme_blk_rw(struct udevice *udev, lbaint_t blknr,
>         c.rw.appmask = 0;
>         c.rw.metadata = 0;
>
> +       /* Always enable FUA for data integrity */
> +       c.rw.control |= NVME_RW_FUA;

I don't think we should blindly enable FUA, instead we should check
whether the Volatile Write Cache is enabled or not, and if enabled,
set FUA, or just completely disable Volatile Write Cache.

> +
>         while (total_lbas) {
>                 if (total_lbas < lbas) {
>                         lbas = (u16)total_lbas;
> --

Regards,
Bin