| Message ID | 1501752663-25088-8-git-send-email-bmeng.cn@gmail.com |
|---|---|
| State | Accepted |
| Commit | beb5f521392e7da208455f3bf0c86bc141c0879d |
| Delegated to: | Tom Rini |
| Headers | show |
On Thu, Aug 03, 2017 at 02:31:02AM -0700, Bin Meng wrote: > 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. On the real NVMe card this is normally not > 0 due to hardware restrictions, but with QEMU emulated NVMe > device it reports as 0. 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); > > dev->max_transfer_shift being 0 will for sure cause lbas to > overflow. Let's use 20. With this fix, the NVMe driver works > on QEMU emulated NVMe device. > > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Tom Rini <trini@konsulko.com>
On Thu, Aug 03, 2017 at 02:31:02AM -0700, Bin Meng wrote: > 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. On the real NVMe card this is normally not > 0 due to hardware restrictions, but with QEMU emulated NVMe > device it reports as 0. 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); > > dev->max_transfer_shift being 0 will for sure cause lbas to > overflow. Let's use 20. With this fix, the NVMe driver works > on QEMU emulated NVMe device. > > Signed-off-by: Bin Meng <bmeng.cn@gmail.com> > Reviewed-by: Tom Rini <trini@konsulko.com> Applied to u-boot/master, thanks!
diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c index bac253a..151fe92 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);
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. On the real NVMe card this is normally not 0 due to hardware restrictions, but with QEMU emulated NVMe device it reports as 0. 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); dev->max_transfer_shift being 0 will for sure cause lbas to overflow. Let's use 20. With this fix, the NVMe driver works on QEMU emulated NVMe device. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> --- drivers/nvme/nvme.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)