Re: [PATCH v2 1/2] Added ETH_SPEED_CAP bitmap in rte_eth_dev_info

[Marc Sune <marc.sune@bisdn.de>]

On 27/05/15 06:02, Thomas Monjalon wrote:
> Hi Marc,
>
> 2015-05-26 21:50, Marc Sune:
>> Added constants and bitmap to struct rte_eth_dev_info to be used by PMDs.
>>
>> Signed-off-by: Marc Sune <marc.sune@bisdn.de>
> [...]
>> +/**
>> + * Device supported speeds
>> + */
>> +#define ETH_SPEED_CAP_NOT_PHY	(0)  /*< No phy media > */
> Why not starting with lower values? Some new drivers may be interested
> by lower speed.

Ok, but which values? 1Mbps FD/HD? Even lower than that?

If you have some NIC(s) in mind with lower values, please point me to 
that and I will collect&add the missing speeds.

>
>> +#define ETH_SPEED_CAP_10M_HD	(1 << 0)  /*< 10 Mbps half-duplex> */
>> +#define ETH_SPEED_CAP_10M_FD	(1 << 1)  /*< 10 Mbps full-duplex> */
>> +#define ETH_SPEED_CAP_100M_HD	(1 << 2)  /*< 100 Mbps half-duplex> */
>> +#define ETH_SPEED_CAP_100M_FD	(1 << 3)  /*< 100 Mbps full-duplex> */
>> +#define ETH_SPEED_CAP_1G	(1 << 4)  /*< 1 Gbps > */
>> +#define ETH_SPEED_CAP_2_5G	(1 << 5)  /*< 2.5 Gbps > */
>> +#define ETH_SPEED_CAP_5G	(1 << 6)  /*< 5 Gbps > */
>> +#define ETH_SPEED_CAP_10G	(1 << 7)  /*< 10 Mbps > */
>> +#define ETH_SPEED_CAP_20G	(1 << 8)  /*< 20 Gbps > */
>> +#define ETH_SPEED_CAP_25G	(1 << 9)  /*< 25 Gbps > */
>> +#define ETH_SPEED_CAP_40G	(1 << 10)  /*< 40 Gbps > */
>> +#define ETH_SPEED_CAP_50G	(1 << 11)  /*< 50 Gbps > */
>> +#define ETH_SPEED_CAP_56G	(1 << 12)  /*< 56 Gbps > */
>> +#define ETH_SPEED_CAP_100G	(1 << 13)  /*< 100 Gbps > */
> We should note that rte_eth_link is using ETH_LINK_SPEED_* constants
> which are not some bitmaps so we have to create these new constants.

Yes, I can add that to the patch description (1/2).

> Furthermore, rte_eth_link.link_speed is an uint16_t so it is limited
> to 40G. Should we use some constant bitmaps here also?

I also thought about converting link_speed into a bitmap to unify the 
constants before starting the patch (there is redundancy), but I wanted 
to be minimally invasive; changing link to a bitmap can break existing apps.

I can also merge them if we think is a better idea.
> What about removing _CAP suffix from your constants?

I added the suffix to make clearer the distinction with link speeds. I 
can remove it if we merge both or if we consider it is not necessary.

>
> [...]
>> +	uint32_t speed_capa;  /**< Supported speeds bitmap (ETH_SPEED_CAP_). */
> If the constants are ETH_SPEED_CAP, why not wording this variable speed_cap?

I followed the convention of the existing rx/tx offload capability bitmaps:

marc@dev:~/git/bisdn/msune/xdpd/libs/dpdk/lib$ grep _capa\; * -R
librte_ether/rte_ethdev.h:    uint32_t rx_offload_capa; /**< Device RX 
offload capabilities. */
librte_ether/rte_ethdev.h:    uint32_t tx_offload_capa; /**< Device TX 
offload capabilities. */

I am fine with speed_cap or speed_caps, but I think we should have some 
consistency on how we name bitmaps.

If we would want to make the bitmaps more explicit, we could define some 
helper typedefs in EAL:

typedef uint16_t bitmap16_t;
typedef uint32_t bitmap32_t;
typedef uint64_t bitmap64_t;

and replace the bitmaps of the structs, again specially the ones used by 
the users.

marc

>