Commit 90646103 authored by Keith Busch's avatar Keith Busch
Browse files

nvme: remove CC register read-back during enabling 



Any non-posted read should flush the previous write, so we don't
necessarily need to read back the value we just wrote. I've found at
least some controllers that respond with 0 for short moments after
writing the CC register with EN (enable) cleared, so the read-back is
overwriting our valid ctrl_config value and ends up breaking on the
subsequent enabling.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent 83340d9c

drivers/nvme/host/core.c

+0 −5
Original line number Diff line number Diff line
@@ -2468,11 +2468,6 @@ int nvme_enable_ctrl(struct nvme_ctrl *ctrl) 
	if (ret)

		return ret;



	/* Flush write to device (required if transport is PCI) */

	ret = ctrl->ops->reg_read32(ctrl, NVME_REG_CC, &ctrl->ctrl_config);

	if (ret)

		return ret;



	/* CAP value may change after initial CC write */

	ret = ctrl->ops->reg_read64(ctrl, NVME_REG_CAP, &ctrl->cap);

	if (ret)