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

[Aaron Williams]

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 | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c
index 7008a54a6d..c94a6d0654 100644
--- a/drivers/nvme/nvme.c
+++ b/drivers/nvme/nvme.c
@@ -75,6 +75,8 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
  int length = total_len;
  int i, nprps;
  length -= (page_size - offset);
+ u32 prps_per_page = (page_size >> 3) - 1;
+ u32 num_pages;

  if (length <= 0) {
   *prp2 = 0;
@@ -90,15 +92,16 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
  }

  nprps = DIV_ROUND_UP(length, page_size);
+ num_pages = (nprps + prps_per_page - 1) / 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;
  }

  prp_pool = dev->prp_pool;
@@ -115,6 +118,7 @@ static int nvme_setup_prps(struct nvme_dev *dev, u64 *prp2,
   nprps--;
  }
  *prp2 = (ulong)dev->prp_pool;
+ flush_dcache_range(*prp2, *prp2 + (num_pages * page_size));

  return 0;
 }
@@ -791,7 +795,7 @@ static int nvme_probe(struct udevice *udev)
  }
  memset(ndev->queues, 0, NVME_Q_NUM * sizeof(struct nvme_queue *));

- ndev->prp_pool = malloc(MAX_PRP_POOL);
+ ndev->prp_pool = memalign(1 << 12, MAX_PRP_POOL);
  if (!ndev->prp_pool) {
   ret = -ENOMEM;
   printf("Error: %s: Out of memory!\n", udev->name);
--
2.16.4