Re: [PATCH net v4] net: stmmac: dwmac-qcom-ethqos: Fix drops in 10M SGMII RX

[Bjorn Andersson]

On Tue, Dec 12, 2023 at 02:52:08PM +0530, Sneh Shah wrote:
> In 10M SGMII mode all the packets are being dropped due to wrong Rx clock.
> SGMII 10MBPS mode needs RX clock divider programmed to avoid drops in Rx.
> Update configure SGMII function with Rx clk divider programming.
> 

Thanks you for the updates!

Reviewed-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>

> Fixes: 463120c31c58 ("net: stmmac: dwmac-qcom-ethqos: add support for SGMII")
> Tested-by: Andrew Halaney <ahalaney@xxxxxxxxxx>
> Signed-off-by: Sneh Shah <quic_snehshah@xxxxxxxxxxx>
> ---
> v4 changelog:
> - Updated commit message to add more details on why 10M SGMII Rx is failing
> - Added a macro for Rx clock divider value
> v3 changelog:
> - Added comment to explain why MAC needs to be reconfigured for SGMII
> v2 changelog:
> - Use FIELD_PREP to prepare bifield values in place of GENMASK
> - Add fixes tag
> ---
>  .../net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c    | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> index d3bf42d0fceb..31631e3f89d0 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> @@ -34,6 +34,7 @@
>  #define RGMII_CONFIG_LOOPBACK_EN		BIT(2)
>  #define RGMII_CONFIG_PROG_SWAP			BIT(1)
>  #define RGMII_CONFIG_DDR_MODE			BIT(0)
> +#define RGMII_CONFIG_SGMII_CLK_DVDR		GENMASK(18, 10)

Thank you for the clarification of rgmii vs sgmii. Perhaps this could be
made clearer by renaming the rgmii ones as well? In a separate patch
series, of course.

Regards,
Bjorn

>  
>  /* SDCC_HC_REG_DLL_CONFIG fields */
>  #define SDCC_DLL_CONFIG_DLL_RST			BIT(30)
> @@ -78,6 +79,8 @@
>  #define ETHQOS_MAC_CTRL_SPEED_MODE		BIT(14)
>  #define ETHQOS_MAC_CTRL_PORT_SEL		BIT(15)
>  
> +#define SGMII_10M_RX_CLK_DVDR			0x31
> +
>  struct ethqos_emac_por {
>  	unsigned int offset;
>  	unsigned int value;
> @@ -598,6 +601,9 @@ static int ethqos_configure_rgmii(struct qcom_ethqos *ethqos)
>  	return 0;
>  }
>  
> +/* On interface toggle MAC registers gets reset.
> + * Configure MAC block for SGMII on ethernet phy link up
> + */
>  static int ethqos_configure_sgmii(struct qcom_ethqos *ethqos)
>  {
>  	int val;
> @@ -617,6 +623,10 @@ static int ethqos_configure_sgmii(struct qcom_ethqos *ethqos)
>  	case SPEED_10:
>  		val |= ETHQOS_MAC_CTRL_PORT_SEL;
>  		val &= ~ETHQOS_MAC_CTRL_SPEED_MODE;
> +		rgmii_updatel(ethqos, RGMII_CONFIG_SGMII_CLK_DVDR,
> +			      FIELD_PREP(RGMII_CONFIG_SGMII_CLK_DVDR,
> +					 SGMII_10M_RX_CLK_DVDR),
> +			      RGMII_IO_MACRO_CONFIG);
>  		break;
>  	}
>  
> -- 
> 2.17.1
>