RE: [PATCH] net/nfp: write link speed to control BAR

[Chaoyong He <chaoyong.he@corigine.com>]

> On 2/21/2023 6:29 AM, Chaoyong He wrote:
> > From: James Hershaw <james.hershaw@corigine.com>
> >
> > Due to changes in the firmware for NFPs, firmware will no longer write
> > the link speed of a port to the control BAR. In line with the
> > behaviour of the kernel NFP driver, this is now handled by the PMD by
> > reading the value provided by the NSP in the nfp_eth_table struct
> > within the pf_dev of the port and subsequently writing this value to the
> control BAR.
> >
> 
> Don't you need some kind of FW version check to figure out if
> 'NFP_NET_CFG_STS_NSP_LINK_RATE' needs to be updated by driver or not?
> 
> How do you manage driver <-> FW dependency?
> 
> 
> > Signed-off-by: James Hershaw <james.hershaw@corigine.com>
> > Reviewed-by: Niklas Söderlund <niklas.soderlund@corigine.com>
> > Reviewed-by: Chaoyong He <chaoyong.he@corigine.com>
> > ---
> >  drivers/net/nfp/nfp_common.c | 90 ++++++++++++++++++++++-----------
> ---
> >  drivers/net/nfp/nfp_ctrl.h   |  9 ++++
> >  2 files changed, 65 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/net/nfp/nfp_common.c
> > b/drivers/net/nfp/nfp_common.c index 5922bfea8e..006ea58008 100644
> > --- a/drivers/net/nfp/nfp_common.c
> > +++ b/drivers/net/nfp/nfp_common.c
> > @@ -52,6 +52,53 @@
> >  #include <sys/ioctl.h>
> >  #include <errno.h>
> >
> > +static const uint32_t nfp_net_link_speed_nfp2rte[] = {
> > +	[NFP_NET_CFG_STS_LINK_RATE_UNSUPPORTED] =
> RTE_ETH_SPEED_NUM_NONE,
> > +	[NFP_NET_CFG_STS_LINK_RATE_UNKNOWN]     =
> RTE_ETH_SPEED_NUM_NONE,
> > +	[NFP_NET_CFG_STS_LINK_RATE_1G]          =
> RTE_ETH_SPEED_NUM_1G,
> > +	[NFP_NET_CFG_STS_LINK_RATE_10G]         =
> RTE_ETH_SPEED_NUM_10G,
> > +	[NFP_NET_CFG_STS_LINK_RATE_25G]         =
> RTE_ETH_SPEED_NUM_25G,
> > +	[NFP_NET_CFG_STS_LINK_RATE_40G]         =
> RTE_ETH_SPEED_NUM_40G,
> > +	[NFP_NET_CFG_STS_LINK_RATE_50G]         =
> RTE_ETH_SPEED_NUM_50G,
> > +	[NFP_NET_CFG_STS_LINK_RATE_100G]        =
> RTE_ETH_SPEED_NUM_100G,
> > +};
> > +
> > +static uint32_t
> > +nfp_net_link_speed_rte2nfp(uint32_t speed) {
> > +	uint32_t i;
> > +
> > +	for (i = 0; i < RTE_DIM(nfp_net_link_speed_nfp2rte); i++) {
> > +		if (speed == nfp_net_link_speed_nfp2rte[i])
> > +			return i;
> > +	}
> > +
> > +	return NFP_NET_CFG_STS_LINK_RATE_UNKNOWN;
> > +}
> > +
> > +static void
> > +nfp_net_notify_port_speed(struct rte_eth_dev *dev) {
> > +	struct nfp_net_hw *hw;
> > +	struct nfp_eth_table *eth_table;
> > +	uint32_t nn_link_status;
> > +
> > +	hw = NFP_NET_DEV_PRIVATE_TO_HW(dev->data->dev_private);
> > +	eth_table = hw->pf_dev->nfp_eth_table;
> > +
> > +	nn_link_status = nn_cfg_readl(hw, NFP_NET_CFG_STS);
> > +	nn_link_status = (nn_link_status >>
> NFP_NET_CFG_STS_LINK_RATE_SHIFT) &
> > +			NFP_NET_CFG_STS_LINK_RATE_MASK;
> > +
> > +	if ((nn_link_status & NFP_NET_CFG_STS_LINK) == 0) {
> > +		nn_cfg_writel(hw, NFP_NET_CFG_STS_NSP_LINK_RATE,
> NFP_NET_CFG_STS_LINK_RATE_UNKNOWN);
> > +		return;
> > +	}
> > +
> > +	nn_cfg_writel(hw, NFP_NET_CFG_STS_NSP_LINK_RATE,
> > +		      nfp_net_link_speed_rte2nfp(eth_table->ports[hw-
> >idx].speed));
> 
> PF driver writes link speed to 'NFP_NET_CFG_STS_NSP_LINK_RATE' register,
> but 'nfp_net_link_update()' still gets it from 'NFP_NET_CFG_STS'
> register (via 'nfp_net_link_speed_nfp2rte[nn_link_status]').
> 
> Shouldn't 'nfp_net_link_update()' needs to be updated to read speed from
> 'NFP_NET_CFG_STS_NSP_LINK_RATE' register?

Sorry for the late response, we spend a lot of time to check and discuss.

For older firmware, a full word is allocated (NFP_NET_CFG_STS) to report link status and port speed to the driver.
However, in the interests of keeping FW files port-speed agnostic in the future, 
the upper 16 bits are no longer written to by FW, so we write the speed to that address (NFP_NET_CFG_STS_LINK_RATE).
The lower 16 bits (link status) are still handled by firmware.

These changes are completely backwards compatible with older firmware versions, so no FW version check is required.