Re: [PATCH net-next] net: stmmac: dwmac-qcom-ethqos: Add support for 2.5G SGMII

[Sneh Shah <quic_snehshah@quicinc.com>]

On 12/20/2023 9:29 PM, Andrew Halaney wrote:
> On Wed, Dec 20, 2023 at 01:02:45PM +0530, Sneh Shah wrote:
>>
>>
>> On 12/18/2023 9:50 PM, Andrew Halaney wrote:
>>> On Mon, Dec 18, 2023 at 12:41:18PM +0530, Sneh Shah wrote:
>>>> Serdes phy needs to operate at 2500 mode for 2.5G speed and 1000
>>>> mode for 1G/100M/10M speed.
>>>> Added changes to configure serdes phy and mac based on link speed.
>>>>
>>>> Signed-off-by: Sneh Shah <quic_snehshah@quicinc.com>
>>>> ---
>>>>  .../stmicro/stmmac/dwmac-qcom-ethqos.c        | 31 +++++++++++++++++--
>>>>  1 file changed, 29 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
>>>> index d3bf42d0fceb..b3a28dc19161 100644
>>>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
>>>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
>>>> @@ -21,6 +21,7 @@
>>>>  #define RGMII_IO_MACRO_CONFIG2		0x1C
>>>>  #define RGMII_IO_MACRO_DEBUG1		0x20
>>>>  #define EMAC_SYSTEM_LOW_POWER_DEBUG	0x28
>>>> +#define ETHQOS_MAC_AN_CTRL		0xE0
>>>>  
>>>>  /* RGMII_IO_MACRO_CONFIG fields */
>>>>  #define RGMII_CONFIG_FUNC_CLK_EN		BIT(30)
>>>> @@ -78,6 +79,10 @@
>>>>  #define ETHQOS_MAC_CTRL_SPEED_MODE		BIT(14)
>>>>  #define ETHQOS_MAC_CTRL_PORT_SEL		BIT(15)
>>>>  
>>>> +/*ETHQOS_MAC_AN_CTRL bits */
>>>> +#define ETHQOS_MAC_AN_CTRL_RAN			BIT(9)
>>>> +#define ETHQOS_MAC_AN_CTRL_ANE			BIT(12)
>>>> +
>>>
>>> nit: space please add a space before ETHQOS_MAC_AN_CTRL
>>>
>> will take care of this in next patch
>>
>>>>  struct ethqos_emac_por {
>>>>  	unsigned int offset;
>>>>  	unsigned int value;
>>>> @@ -109,6 +114,7 @@ struct qcom_ethqos {
>>>>  	unsigned int num_por;
>>>>  	bool rgmii_config_loopback_en;
>>>>  	bool has_emac_ge_3;
>>>> +	unsigned int serdes_speed;
> 
> Another nit as I look closer: I think this should be grouped by phy_mode
> etc just for readability.
Didn't get this. can you please elaborate more?
> 
>>>>  };
>>>>  
>>>>  static int rgmii_readl(struct qcom_ethqos *ethqos, unsigned int offset)
>>>> @@ -600,27 +606,47 @@ static int ethqos_configure_rgmii(struct qcom_ethqos *ethqos)
>>>>  
>>>>  static int ethqos_configure_sgmii(struct qcom_ethqos *ethqos)
>>>>  {
>>>> -	int val;
>>>> -
>>>> +	int val, mac_an_value;
>>>>  	val = readl(ethqos->mac_base + MAC_CTRL_REG);
>>>> +	mac_an_value = readl(ethqos->mac_base + ETHQOS_MAC_AN_CTRL);
>>>>  
>>>>  	switch (ethqos->speed) {
>>>> +	case SPEED_2500:
>>>> +		val &= ~ETHQOS_MAC_CTRL_PORT_SEL;
>>>> +		rgmii_updatel(ethqos, RGMII_CONFIG2_RGMII_CLK_SEL_CFG,
>>>> +			      RGMII_CONFIG2_RGMII_CLK_SEL_CFG,
>>>> +			      RGMII_IO_MACRO_CONFIG2);
>>>> +		if (ethqos->serdes_speed != SPEED_2500)
>>>> +			phy_set_speed(ethqos->serdes_phy, ethqos->speed);
>>>> +		mac_an_value &= ~ETHQOS_MAC_AN_CTRL_ANE;
>>>> +		break;
>>>>  	case SPEED_1000:
>>>>  		val &= ~ETHQOS_MAC_CTRL_PORT_SEL;
>>>>  		rgmii_updatel(ethqos, RGMII_CONFIG2_RGMII_CLK_SEL_CFG,
>>>>  			      RGMII_CONFIG2_RGMII_CLK_SEL_CFG,
>>>>  			      RGMII_IO_MACRO_CONFIG2);
>>>> +		if (ethqos->serdes_speed != SPEED_1000)
>>>> +			phy_set_speed(ethqos->serdes_phy, ethqos->speed);
>>>> +		mac_an_value |= ETHQOS_MAC_AN_CTRL_RAN | ETHQOS_MAC_AN_CTRL_ANE;
>>>>  		break;
>>>>  	case SPEED_100:
>>>>  		val |= ETHQOS_MAC_CTRL_PORT_SEL | ETHQOS_MAC_CTRL_SPEED_MODE;
>>>> +		if (ethqos->serdes_speed != SPEED_1000)
>>>> +			phy_set_speed(ethqos->serdes_phy, ethqos->speed);
>>>> +		mac_an_value |= ETHQOS_MAC_AN_CTRL_RAN | ETHQOS_MAC_AN_CTRL_ANE;
>>>>  		break;
>>>>  	case SPEED_10:
>>>>  		val |= ETHQOS_MAC_CTRL_PORT_SEL;
>>>>  		val &= ~ETHQOS_MAC_CTRL_SPEED_MODE;
>>>> +		if (ethqos->serdes_speed != SPEED_1000)
>>>> +			phy_set_speed(ethqos->serdes_phy, ethqos->speed);
>>>> +		mac_an_value |= ETHQOS_MAC_AN_CTRL_RAN | ETHQOS_MAC_AN_CTRL_ANE;
>>>>  		break;
>>>>  	}
>>>>  
>>>>  	writel(val, ethqos->mac_base + MAC_CTRL_REG);
>>>> +	writel(mac_an_value, ethqos->mac_base + ETHQOS_MAC_AN_CTRL);
>>>> +	ethqos->serdes_speed = ethqos->speed;
>>>
>>> I see these bits are generic and there's some functions in stmmac_pcs.h
>>> that muck with these...
>>>
>>> Could you help me understand if this really should be Qualcomm specific,
>>> or if this is something that should be considered for the more core bits
>>> of the driver? I feel in either case we should take advantage of the
>>> common definitions in that file if possible.
>>>
>> we do have function dwmac_ctrl_ane in core driver which updates same registers. However, it does not have the option to reset ANE bit, it can only set bits. For SPEED_2500 we need to reset ANE bit. Hence I am adding it here. Not sure if we can extend dwmac_ctrl_ane function to reset bits as well.
> 
> I'd evaluate if you can update that function to clear the ANE bit when
> the ane boolean is false. From the usage I see I feel that makes sense,
> but correct me if you think I'm wrong.
> At the very least let's use the defines from there, and possibly add a
> new function if clearing is not acceptable in dwmac_ctrl_ane().
> 
> Stepping back, I was asking in general is the need to muck with ANE here
> is a Qualcomm specific problem, or is that a generic thing that should be
> handled in the core (and the phy_set_speed() bit stay here)? i.e. would
> any dwmac5 based IP need to do something like this for SPEED_2500?
I think disabling ANE for SPEED_2500 is generic not specific to qualcomm. Even in dwxgmac2 versions also we need to disable ANE for SPEED_2500. Autoneg clause 37 stadard doesn't support 2500 speed. So we need to disable autoneg for speed 2500

> 
>>>>  
>>>>  	return val;
>>>>  }
>>>> @@ -789,6 +815,7 @@ static int qcom_ethqos_probe(struct platform_device *pdev)
>>>>  				     "Failed to get serdes phy\n");
>>>>  
>>>>  	ethqos->speed = SPEED_1000;
>>>> +	ethqos->serdes_speed = SPEED_1000;
>>>>  	ethqos_update_link_clk(ethqos, SPEED_1000);
>>>>  	ethqos_set_func_clk_en(ethqos);
>>>>  
>>>> -- 
>>>> 2.17.1
>>>>
>>>
>>
>