ethdev: refine API to query supported packet types

This change is to  make user code simpler. For PMDs which do not fill any
packet types, return 0 instead of -ENOTSUP as suggested by Bruce.

Usually, users only care if the required (by ptype_mask) ptypes can be
filled by the specified PMD. If the PMD implements dev_supported_ptypes_get
func is not important. And the introduce of another return value (-ENOTSUP)
would increase the complexity of user programs to check it.

Besides, there are ways to know if a PMD implements the func:
  a. see doc/guides/nics/overview.rst.
  b. use (~1) as parameter ptype_mask, then check if return 0.

Fixes: 78a38edf66de ("ethdev: query supported packet types")

Suggested-by: Bruce Richardson <bruce.richardson@intel.com>
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
index dcf9e6f..bd54e1f 100644 (file)
--- a/lib/librte_ether/rte_ethdev.c
+++ b/lib/librte_ether/rte_ethdev.c
@@ -1670,8 +1670,7 @@ rte_eth_dev_get_supported_ptypes(uint8_t port_id, uint32_t ptype_mask,
 
        RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
        dev = &rte_eth_devices[port_id];
-       RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_supported_ptypes_get,
-                               -ENOTSUP);
+       RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_supported_ptypes_get, 0);
        all_ptypes = (*dev->dev_ops->dev_supported_ptypes_get)(dev);
 
        if (!all_ptypes)

diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index 37ddd51..022733e 100644 (file)
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -2379,6 +2379,9 @@ void rte_eth_dev_info_get(uint8_t port_id, struct rte_eth_dev_info *dev_info);
  * @note
  *   Better to invoke this API after the device is already started or rx burst
  *   function is decided, to obtain correct supported ptypes.
+ * @note
+ *   if a given PMD does not report what ptypes it supports, then the supported
+ *   ptype count is reported as 0.
  * @param port_id
  *   The port identifier of the Ethernet device.
  * @param ptype_mask
@@ -2388,9 +2391,9 @@ void rte_eth_dev_info_get(uint8_t port_id, struct rte_eth_dev_info *dev_info);
  * @param num
  *  Size of the array pointed by param ptypes.
  * @return
- *   - (>0) Number of supported ptypes. If it exceeds param num, exceeding
- *          packet types will not be filled in the given array.
- *   - (0 or -ENOTSUP) if PMD does not fill the specified ptype.
+ *   - (>=0) Number of supported ptypes. If the number of types exceeds num,
+ *           only num entries will be filled into the ptypes array, but the full
+ *           count of supported ptypes will be returned.
  *   - (-ENODEV) if *port_id* invalid.
  */
 int rte_eth_dev_get_supported_ptypes(uint8_t port_id, uint32_t ptype_mask,