* Re: [PATCH net v2 1/1] net: pcs: xpcs: fix incorrect CL37 AN sequence
2021-09-29 12:05 [PATCH net v2 1/1] net: pcs: xpcs: fix incorrect CL37 AN sequence Wong Vee Khee
@ 2021-09-29 13:13 ` Vladimir Oltean
0 siblings, 0 replies; 2+ messages in thread
From: Vladimir Oltean @ 2021-09-29 13:13 UTC (permalink / raw)
To: Wong Vee Khee
Cc: Jose Abreu, Andrew Lunn, Heiner Kallweit, Russell King,
David S . Miller, Jakub Kicinski, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Wong Vee Khee, Wong Vee Khee
On Wed, Sep 29, 2021 at 08:05:34PM +0800, Wong Vee Khee wrote:
> According to Synopsys DesignWare Cores Ethernet PCS databook, it is
> required to disable Clause 37 auto-negotiation by programming bit-12
> (AN_ENABLE) to 0 if it is already enabled, before programming various
> fields of VR_MII_AN_CTRL registers.
>
> After all these programming are done, it is then required to enable
> Clause 37 auto-negotiation by programming bit-12 (AN_ENABLE) to 1.
>
> Cc: Vladimir Oltean <vladimir.oltean@nxp.com>
> Signed-off-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
> ---
netdev/fixes_present fail Series targets non-next tree, but doesn't contain any Fixes tags
https://patchwork.kernel.org/project/netdevbpf/patch/20210929120534.411157-1-vee.khee.wong@linux.intel.com/
> v1 -> v2:
> - Removed use of xpcs_modify() helper function.
> - Add conditional check on inband auto-negotiation.
>
> drivers/net/pcs/pcs-xpcs.c | 30 ++++++++++++++++++++++++++----
> 1 file changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
> index fb0a83dc09ac..f34d5caeaba1 100644
> --- a/drivers/net/pcs/pcs-xpcs.c
> +++ b/drivers/net/pcs/pcs-xpcs.c
> @@ -700,11 +700,14 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
> int ret;
>
> /* For AN for C37 SGMII mode, the settings are :-
> - * 1) VR_MII_AN_CTRL Bit(2:1)[PCS_MODE] = 10b (SGMII AN)
> - * 2) VR_MII_AN_CTRL Bit(3) [TX_CONFIG] = 0b (MAC side SGMII)
> + * 1) VR_MII_MMD_CTRL Bit(12) [AN_ENABLE] = 0b (Disable SGMII AN in case
> + it is already enabled)
> + * 2) VR_MII_AN_CTRL Bit(2:1)[PCS_MODE] = 10b (SGMII AN)
> + * 3) VR_MII_AN_CTRL Bit(3) [TX_CONFIG] = 0b (MAC side SGMII)
> * DW xPCS used with DW EQoS MAC is always MAC side SGMII.
> - * 3) VR_MII_DIG_CTRL1 Bit(9) [MAC_AUTO_SW] = 1b (Automatic
> + * 4) VR_MII_DIG_CTRL1 Bit(9) [MAC_AUTO_SW] = 1b (Automatic
> * speed/duplex mode change by HW after SGMII AN complete)
> + * 5) VR_MII_MMD_CTRL Bit(12) [AN_ENABLE] = 1b (Enable SGMII AN)
> *
> * Note: Since it is MAC side SGMII, there is no need to set
> * SR_MII_AN_ADV. MAC side SGMII receives AN Tx Config from
> @@ -712,6 +715,12 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
> * between PHY and Link Partner. There is also no need to
> * trigger AN restart for MAC-side SGMII.
> */
> + ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL);
> + if (ret < 0)
> + return ret;
> + ret &= ~AN_CL37_EN;
> + xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL, ret);
For consistency can you please check the return code from this xpcs_write too?
> +
> ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_AN_CTRL);
> if (ret < 0)
> return ret;
> @@ -736,7 +745,20 @@ static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs, unsigned int mode)
> else
> ret &= ~DW_VR_MII_DIG_CTRL1_MAC_AUTO_SW;
>
> - return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
> + ret = xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_DIG_CTRL1, ret);
> + if (ret < 0)
> + return ret;
> +
> + ret = xpcs_read(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL);
> + if (ret < 0)
> + return ret;
> +
> + if (phylink_autoneg_inband(mode))
> + ret |= AN_CL37_EN;
> + else
> + ret &= ~AN_CL37_EN;
> +
> + return xpcs_write(xpcs, MDIO_MMD_VEND2, DW_VR_MII_MMD_CTRL, ret);
Not sure whether this is too much for "net" or not, but I suppose it is
pretty much relevant.
Clearing AN_CL37_EN during the first step is only necessary if it was
set in the first place. Otherwise, you could do only the xpcs_read but
not the xpcs_write.
At the end, you don't really need to read DW_VR_MII_MMD_CTRL again, you
just read it above, didn't you, can't you save it in a local variable?
And you only need to perform the write if the state of the AN_CL37_EN
bit changed, i.e. it was 0 before, and is now 1.
What I'm trying to say is that for the sja1105 driver, the XPCS is
accessed over SPI commands, and I would like for the number of those to
be minimized if possible. Thanks.
I've tested the change and it still works, by the way. I will add the
appropriate tags when you resend the v3.
> }
>
> static int xpcs_config_2500basex(struct dw_xpcs *xpcs)
> --
> 2.25.1
>
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