09/09/2021 15:54, fengchengwen:

On 2021/9/9 20:45, Bruce Richardson wrote:

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On Thu, Sep 09, 2021 at 01:29:33PM +0200, Thomas Monjalon wrote:

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09/09/2021 13:18, Bruce Richardson:

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On Thu, Sep 09, 2021 at 12:33:00PM +0200, Thomas Monjalon wrote:

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07/09/2021 14:56, Chengwen Feng:

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+ * The first three APIs are used to submit the operation request to the virtual
+ * DMA channel, if the submission is successful, an uint16_t ring_idx is
+ * returned, otherwise a negative number is returned.

unsigned or negative? looks weird.

May be, but it works well. We could perhaps rephase to make it less weird
though:
"if the submission is successful, a positive ring_idx <= UINT16_MAX is
 returned, otherwise a negative number is returned."

I am advocating for int16_t,
it makes a lot of things simpler.

No, it doesn't work as you can't have wrap-around of the IDs once you use
signed values - and that impacts both the end app and the internals of the
drivers. Let's keep it as-is otherwise it will have massive impacts -
including potential perf impacts.

Not sure to understand what you mean.
Please could you explain what does not work and what is the perf impact?
I guess you want unsigned index for rings, then OK.
For device ID however, I believe signed integer is useful.

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+bool
+rte_dmadev_is_valid_dev(uint16_t dev_id);

I would suggest dropping the final "_dev" in the function name.

The alternative, which I would support, is replacing "rte_dmadev" with
"rte_dma" across the API. This would then become "rte_dma_is_valid_dev"
which is clearer, since the dev is not part of the standard prefix. It also
would fit in with a possible future function of "rte_dma_is_valid_vchan"
for instance.

Yes
The question is whether it would make sense to reserver rte_dma_ prefix
for some DMA functions which would be outside of dmadev lib?
If you think that all DMA functions will be in dmadev,
then yes we can shorten the prefix to rte_dma_.

Well, any DPDK dma functions which are not in dma library should have the
prefix of the library they are in e.g. rte_eal_dma_*, rte_pci_dma_*

Quite often, we skip the eal_ prefix, that's why I was thinking about
a possible namespace conflict. Anyway it could be managed.

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Therefore, I don't think name conflicts should be an issue, and I like
having less typing to do in function names (and I believe Morten was
strongly proposing this previously too)

The dmadev is rather short, if change I prefer all public API with rte_dma_ prefix,
and don't have rte_dma_dev_ prefix for such start/stop/close. (ps: the rte_eth_ also
have rte_eth_dev_close which is painful for OCD).

Yes OK for rte_dma_ prefix everywhere.

Also should the filename(e.g. rte_dmadev.h) and directory-name(lib/dmadev) also change ?

I believe it's better to keep dmadev as name of the lib and filename,
so it's consistent with other device classes.
What are the other opinions?