At the moment the nvme_get_features() and nvme_set_features() functions carry a (somewhat misleading) comment about missing cache maintenance.
As it turns out, nvme_get_features() has no caller at all in the tree, and nvme_set_features' only user doesn't use a DMA buffer.
Mention that in the comment, and leave some breadcrumbs for the future, should those functions attract more users.
Signed-off-by: Andre Przywara andre.przywara@arm.com --- Hi,
just extending the comments as this caused some confusion lately, and to keep the pointer to the NVMe spec I checked.
Cheers, Andre
drivers/nvme/nvme.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/nvme/nvme.c b/drivers/nvme/nvme.c index 5d6331ad346..3ff3d5de08e 100644 --- a/drivers/nvme/nvme.c +++ b/drivers/nvme/nvme.c @@ -481,6 +481,7 @@ int nvme_get_features(struct nvme_dev *dev, unsigned fid, unsigned nsid, dma_addr_t dma_addr, u32 *result) { struct nvme_command c; + int ret;
memset(&c, 0, sizeof(c)); c.features.opcode = nvme_admin_get_features; @@ -488,12 +489,20 @@ int nvme_get_features(struct nvme_dev *dev, unsigned fid, unsigned nsid, c.features.prp1 = cpu_to_le64(dma_addr); c.features.fid = cpu_to_le32(fid);
+ ret = nvme_submit_admin_cmd(dev, &c, result); + /* - * TODO: add cache invalidate operation when the size of - * the DMA buffer is known + * TODO: Add some cache invalidation when a DMA buffer is involved + * in the request, here and before the command gets submitted. The + * buffer size varies by feature, also some features use a different + * field in the command packet to hold the buffer address. + * Section 5.21.1 (Set Features command) in the NVMe specification + * details the buffer requirements for each feature. + * + * At the moment there is no user of this function. */
- return nvme_submit_admin_cmd(dev, &c, result); + return ret; }
int nvme_set_features(struct nvme_dev *dev, unsigned fid, unsigned dword11, @@ -508,8 +517,14 @@ int nvme_set_features(struct nvme_dev *dev, unsigned fid, unsigned dword11, c.features.dword11 = cpu_to_le32(dword11);
/* - * TODO: add cache flush operation when the size of - * the DMA buffer is known + * TODO: Add a cache clean (aka flush) operation when a DMA buffer is + * involved in the request. The buffer size varies by feature, also + * some features use a different field in the command packet to hold + * the buffer address. Section 5.21.1 (Set Features command) in the + * NVMe specification details the buffer requirements for each + * feature. + * At the moment the only user of this function is not using + * any DMA buffer at all. */
return nvme_submit_admin_cmd(dev, &c, result);