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nvme: Elaborate on cache maintenance operation in get/set_features 

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>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Andre Przywara 2021-03-02 15:43:43 +00:00 committed by Tom Rini
parent d0c04926cd
commit 4c49879689
1 changed files with 20 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/nvme/nvme.c
View File

@ -489,6 +489,7 @@ 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;
@ -496,12 +497,20 @@ 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,
@ -516,8 +525,14 @@ 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);