Re: [PATCH v2 2/2] net/nfp: write link speed to control BAR

[Ferruh Yigit]

On 3/10/2023 6:25 AM, Chaoyong He wrote:
> +     /**
> +      * Shift and mask nn_link_status so that it is effectively the value
> +      * at offset NFP_NET_CFG_STS_NSP_LINK_RATE.
> +      */
> +     nn_link_status = (nn_link_status >> NFP_NET_CFG_STS_LINK_RATE_SHIFT) &
> +                      NFP_NET_CFG_STS_LINK_RATE_MASK;

Thanks for extensive commenting, perhaps this is the source of
confusion, I can't see how above logic makes effectively the value at
offset LINK_RATE.

NFP_NET_CFG_STS_LINK_RATE_SHIFT = 1
NFP_NET_CFG_STS_LINK_RATE_MASK  = 0xF

NFP_NET_CFG_STS               = 0x34
NFP_NET_CFG_STS_NSP_LINK_RATE = 0x36

nfp_net_notify_port_speed()
        uint16_t speed;
        *(0x36) = speed

nfp_net_link_update()
        uint16_t val = *(0x34)
        val = (val >> 1) & 0xF;


How come 'speed' and 'val' are same value?

Either there is a mistake or FW is making something in the background, I
am trying to clarify this in past few comments but not able to yet.