[U-Boot] [PATCH] nvme: Fix PRP Offset Invalid

[Bin Meng]

Hi Aaron,

On Wed, Aug 21, 2019 at 10:09 PM Aaron Williams <awilliams at marvell.com> wrote:
>
> From: Aaron Williams <aaron.williams at cavium.com>
>
> When large writes take place I saw a Samsung EVO 970+ return a status
> value of 0x13, PRP Offset Invalid.  I tracked this down to the
> improper handling of PRP entries.  The blocks the PRP entries are
> placed in cannot cross a page boundary and thus should be allocated
> on page boundaries.  This is how the Linux kernel driver works.
>
> With this patch, the PRP pool is allocated on a page boundary and
> other than the very first allocation, the pool size is a multiple of
> the page size.  Each page can hold (4096 / 8) - 1 entries since the
> last entry must point to the next page in the pool.
>
> Change-Id: I8df66c87d6a6105da556d327d4cc5148e444d20e
> Signed-off-by: Aaron Williams <awilliams at marvell.com>
> ---
>  drivers/nvme/nvme.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
> index 7008a54a6d..71ea226820 100644
> --- a/drivers/nvme/nvme.c
> +++ b/drivers/nvme/nvme.c
> @@ -74,6 +74,9 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
>         u64 *prp_pool;
>         int length = total_len;
>         int i, nprps;
> +       u32 prps_per_page = (page_size >> 3) - 1;
> +       u32 num_pages;
> +
>         length -= (page_size - offset);
>
>         if (length <= 0) {
> @@ -90,15 +93,16 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
>         }
>
>         nprps = DIV_ROUND_UP(length, page_size);
> +       num_pages = DIV_ROUND_UP(nprps, prps_per_page);
>
>         if (nprps > dev->prp_entry_num) {
>                 free(dev->prp_pool);
> -               dev->prp_pool = malloc(nprps << 3);
> +               dev->prp_pool = memalign(page_size, num_pages * page_size);
>                 if (!dev->prp_pool) {
>                         printf("Error: malloc prp_pool fail\n");
>                         return -ENOMEM;
>                 }
> -               dev->prp_entry_num = nprps;
> +               dev->prp_entry_num = ((page_size >> 3) - 1) * num_pages;

This should be: dev->prp_entry_num = prps_per_page * num_pages;

When you respin the patch, please add the version number in the email
title so that we can have a better track. Thanks!

>         }

[snip]

Regards,
Bin