diff options
| -rw-r--r-- | drivers/nvme/nvme.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c index bac253a3f7..151fe92479 100644 --- a/drivers/nvme/nvme.c +++ b/drivers/nvme/nvme.c @@ -563,6 +563,27 @@ static int nvme_get_info_from_identify(struct nvme_dev *dev) memcpy(dev->firmware_rev, ctrl->fr, sizeof(ctrl->fr)); if (ctrl->mdts) dev->max_transfer_shift = (ctrl->mdts + shift); + else { + /* + * Maximum Data Transfer Size (MDTS) field indicates the maximum + * data transfer size between the host and the controller. The + * host should not submit a command that exceeds this transfer + * size. The value is in units of the minimum memory page size + * and is reported as a power of two (2^n). + * + * The spec also says: a value of 0h indicates no restrictions + * on transfer size. But in nvme_blk_read/write() below we have + * the following algorithm for maximum number of logic blocks + * per transfer: + * + * u16 lbas = 1 << (dev->max_transfer_shift - ns->lba_shift); + * + * In order for lbas not to overflow, the maximum number is 15 + * which means dev->max_transfer_shift = 15 + 9 (ns->lba_shift). + * Let's use 20 which provides 1MB size. + */ + dev->max_transfer_shift = 20; + } /* Apply quirk stuff */ dm_pci_read_config16(dev->pdev, PCI_VENDOR_ID, &vendor); |