Subject: Re: [PATCH] net: stmmac: add dcrs parameter

From: Giuseppe CAVALLARO <[email-masked]>
Date: Mon, 25 Aug 2014 14:23:39 +0200

Hello

On 8/25/2014 1:50 PM, Ley Foon Tan wrote:
> This patch add the option to enable DCRS bit in GMAC control register.
> Default is disabled if snps,dcrs is not defined.
>
> For MII, Carrier Sense (CRS) must be asserted during transmission
> whereas in RGMII, CRS is not. RGMII does not provide a way to signal
> loss of carrier during a transmission.
>
> When DCRS bit set high in control register, the MAC transmitter
> ignore the (G)MII Carrier Sense signal during frame transmission
> in the half-duplex mode. This request results in no errors generated
> because of Loss of Carrier or No Carrier during such transmission.

We have to add this fix in the driver. I wonder if we can avoid to have
another parameter and just have it set as default
(http://git.stlinux.com/?p=stm/linux-sh4-2.6.32.y.git;a=commit;h=b0b863bf65c36dc593f6b7b4b418394fd880dae2)
Or we could touch this bit according to the link duplex negotiated and
the phy mode selected.

peppe

>
> Signed-off-by: Ley Foon Tan <[email-masked]>
> ---
>   Documentation/devicetree/bindings/net/stmmac.txt      | 4 ++++
>   drivers/net/ethernet/stmicro/stmmac/common.h          | 3 ++-
>   drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c  | 4 +++-
>   drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 3 ++-
>   drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 2 ++
>   include/linux/stmmac.h                                | 1 +
>   6 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
> index 9b03c57..a68e720 100644
> --- a/Documentation/devicetree/bindings/net/stmmac.txt
> +++ b/Documentation/devicetree/bindings/net/stmmac.txt
> @@ -39,6 +39,10 @@ Optional properties:
>     further clocks may be specified in derived bindings.
>   - clock-names: One name for each entry in the clocks property, the
>     first one should be "stmmaceth".
> +- snps,dcrs: Enable DCRS bit in GMAC control register. This DCRS bit makes the
> +	MAC transmitter ignore the (G)MII CRS signal during frame transmission
> +	in the half-duplex mode. This request results in no errors generated
> +	because of Loss of Carrier or No Carrier during such transmission.
>
>   Examples:
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
> index de507c3..9abe221 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/common.h
> +++ b/drivers/net/ethernet/stmicro/stmmac/common.h
> @@ -445,10 +445,11 @@ struct mac_device_info {
>   	int multicast_filter_bins;
>   	int unicast_filter_entries;
>   	int mcast_bits_log2;
> +	int dcrs;
>   };
>
>   struct mac_device_info *dwmac1000_setup(void __iomem *ioaddr, int mcbins,
> -					int perfect_uc_entries);
> +					int perfect_uc_entries, int dcrs);
>   struct mac_device_info *dwmac100_setup(void __iomem *ioaddr);
>
>   void stmmac_set_mac_addr(void __iomem *ioaddr, u8 addr[6],
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
> index d8ef187..924d450 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
> @@ -37,6 +37,7 @@ static void dwmac1000_core_init(struct mac_device_info *hw, int mtu)
>   	void __iomem *ioaddr = hw->pcsr;
>   	u32 value = readl(ioaddr + GMAC_CONTROL);
>   	value |= GMAC_CORE_INIT;
> +	value |= hw->dcrs;
>   	if (mtu > 1500)
>   		value |= GMAC_CONTROL_2K;
>   	if (mtu > 2000)
> @@ -409,7 +410,7 @@ static const struct stmmac_ops dwmac1000_ops = {
>   };
>
>   struct mac_device_info *dwmac1000_setup(void __iomem *ioaddr, int mcbins,
> -					int perfect_uc_entries)
> +					int perfect_uc_entries, int dcrs)
>   {
>   	struct mac_device_info *mac;
>   	u32 hwid = readl(ioaddr + GMAC_VERSION);
> @@ -422,6 +423,7 @@ struct mac_device_info *dwmac1000_setup(void __iomem *ioaddr, int mcbins,
>   	mac->multicast_filter_bins = mcbins;
>   	mac->unicast_filter_entries = perfect_uc_entries;
>   	mac->mcast_bits_log2 = 0;
> +	mac->dcrs = dcrs;
>
>   	if (mac->multicast_filter_bins)
>   		mac->mcast_bits_log2 = ilog2(mac->multicast_filter_bins);
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 08addd6..bf35b19 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2600,7 +2600,8 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
>   		priv->dev->priv_flags |= IFF_UNICAST_FLT;
>   		mac = dwmac1000_setup(priv->ioaddr,
>   				      priv->plat->multicast_filter_bins,
> -				      priv->plat->unicast_filter_entries);
> +				      priv->plat->unicast_filter_entries,
> +				      priv->plat->dcrs);
>   	} else {
>   		mac = dwmac100_setup(priv->ioaddr);
>   	}
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index bb524a9..07f895f 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -227,6 +227,8 @@ static int stmmac_probe_config_dt(struct platform_device *pdev,
>   		pr_warn("force_sf_dma_mode is ignored if force_thresh_dma_mode is set.");
>   	}
>
> +	plat->dcrs = of_property_read_bool(np, "snps,dcrs");
> +
>   	return 0;
>   }
>   #else
> diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
> index cd63851..6367f42 100644
> --- a/include/linux/stmmac.h
> +++ b/include/linux/stmmac.h
> @@ -114,6 +114,7 @@ struct plat_stmmacenet_data {
>   	int maxmtu;
>   	int multicast_filter_bins;
>   	int unicast_filter_entries;
> +	int dcrs;
>   	void (*fix_mac_speed)(void *priv, unsigned int speed);
>   	void (*bus_setup)(void __iomem *ioaddr);
>   	void *(*setup)(struct platform_device *pdev);
>