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nvme: set dma alignment to qword

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The default dma alignment mask is 511, which is much larger than any nvme
controller requires. NVMe controllers accept qword aligned DMA addresses,
so set the request_queue constraints to that. This can help avoid bounce
buffers on user passthrough commands.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Keith Busch 2020-05-20 19:22:53 -07:00 committed by Christoph Hellwig
parent 1cdf9f7670
commit 3b2a1ebceb
1 changed files with 1 additions and 0 deletions
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drivers/nvme/host/core.c
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@ -2322,6 +2322,7 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
blk_queue_max_segments(q, min_t(u32, max_segments, USHRT_MAX));
}
blk_queue_virt_boundary(q, ctrl->page_size - 1);
blk_queue_dma_alignment(q, 7);
if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
vwc = true;
blk_queue_write_cache(q, vwc, vwc);