Re: [Intel-wired-lan] [PATCH iwl-net v2 1/1] e1000e: fix force smbus during suspend flow

[Mor Bar-Gabay <morx.bar.gabay@intel.com>]

On 20/06/2024 9:36, Vitaly Lifshits wrote:
> Commit 861e8086029e ("e1000e: move force SMBUS from enable ulp function
> to avoid PHY loss issue") resolved a PHY access loss during suspend on
> Meteor Lake consumer platforms, but it affected corporate systems
> incorrectly.
> 
> A better fix, working for both consumer and corporate systems, was
> proposed in commit bfd546a552e1 ("e1000e: move force SMBUS near the end
> of enable_ulp function"). However, it introduced a regression on older
> devices, such as [8086:15B8], [8086:15F9], [8086:15BE].
> 
> This patch aims to fix the secondary regression, by limiting the scope of
> the changes to Meteor Lake platforms only.
> 
> Fixes: bfd546a552e1 ("e1000e: move force SMBUS near the end of enable_ulp function")
> Reported-by: Todd Brandt <todd.e.brandt@intel.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218940
> Reported-by: Dieter Mummenschanz <dmummenschanz@web.de>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218936
> Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
> Reported-by: Todd Brandt <todd.e.brandt@intel.com>
> Reported-by: Dieter Mummenschanz <dmummenschanz@web.de>
> Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
> ---
> v2: enhance the function description and address community comments
> v1: initial version
> ---
>   drivers/net/ethernet/intel/e1000e/ich8lan.c | 73 +++++++++++++++------
>   1 file changed, 53 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.c b/drivers/net/ethernet/intel/e1000e/ich8lan.c
> index 2e98a2a0bead..86d4ae95b45a 100644
> --- a/drivers/net/ethernet/intel/e1000e/ich8lan.c
> +++ b/drivers/net/ethernet/intel/e1000e/ich8lan.c
> @@ -137,6 +137,7 @@ static void e1000_gate_hw_phy_config_ich8lan(struct e1000_hw *hw, bool gate);
>   static s32 e1000_disable_ulp_lpt_lp(struct e1000_hw *hw, bool force);
>   static s32 e1000_setup_copper_link_pch_lpt(struct e1000_hw *hw);
>   static s32 e1000_oem_bits_config_ich8lan(struct e1000_hw *hw, bool d0_state);
> +static s32 e1000e_force_smbus(struct e1000_hw *hw);
>   
>   static inline u16 __er16flash(struct e1000_hw *hw, unsigned long reg)
>   {
> @@ -1108,6 +1109,46 @@ static s32 e1000_platform_pm_pch_lpt(struct e1000_hw *hw, bool link)
>   	return 0;
>   }
>   
> +/**
> + *  e1000e_force_smbus - Force interfaces to transition to SMBUS mode.
> + *  @hw: pointer to the HW structure
> + *
> + *  Force the MAC and the PHY to SMBUS mode. Assumes semaphore already
> + *  acquired.
> + *
> + * Return: 0 on success, negative errno on failure.
> + **/
> +static s32 e1000e_force_smbus(struct e1000_hw *hw)
> +{
> +	u16 smb_ctrl = 0;
> +	u32 ctrl_ext;
> +	s32 ret_val;
> +
> +	/* Switching PHY interface always returns MDI error
> +	 * so disable retry mechanism to avoid wasting time
> +	 */
> +	e1000e_disable_phy_retry(hw);
> +
> +	/* Force SMBus mode in the PHY */
> +	ret_val = e1000_read_phy_reg_hv_locked(hw, CV_SMB_CTRL, &smb_ctrl);
> +	if (ret_val) {
> +		e1000e_enable_phy_retry(hw);
> +		return ret_val;
> +	}
> +
> +	smb_ctrl |= CV_SMB_CTRL_FORCE_SMBUS;
> +	e1000_write_phy_reg_hv_locked(hw, CV_SMB_CTRL, smb_ctrl);
> +
> +	e1000e_enable_phy_retry(hw);
> +
> +	/* Force SMBus mode in the MAC */
> +	ctrl_ext = er32(CTRL_EXT);
> +	ctrl_ext |= E1000_CTRL_EXT_FORCE_SMBUS;
> +	ew32(CTRL_EXT, ctrl_ext);
> +
> +	return 0;
> +}
> +
>   /**
>    *  e1000_enable_ulp_lpt_lp - configure Ultra Low Power mode for LynxPoint-LP
>    *  @hw: pointer to the HW structure
> @@ -1165,6 +1206,14 @@ s32 e1000_enable_ulp_lpt_lp(struct e1000_hw *hw, bool to_sx)
>   	if (ret_val)
>   		goto out;
>   
> +	if (hw->mac.type != e1000_pch_mtp) {
> +		ret_val = e1000e_force_smbus(hw);
> +		if (ret_val) {
> +			e_dbg("Failed to force SMBUS: %d\n", ret_val);
> +			goto release;
> +		}
> +	}
> +
>   	/* Si workaround for ULP entry flow on i127/rev6 h/w.  Enable
>   	 * LPLU and disable Gig speed when entering ULP
>   	 */
> @@ -1225,27 +1274,11 @@ s32 e1000_enable_ulp_lpt_lp(struct e1000_hw *hw, bool to_sx)
>   	}
>   
>   release:
> -	/* Switching PHY interface always returns MDI error
> -	 * so disable retry mechanism to avoid wasting time
> -	 */
> -	e1000e_disable_phy_retry(hw);
> -
> -	/* Force SMBus mode in PHY */
> -	ret_val = e1000_read_phy_reg_hv_locked(hw, CV_SMB_CTRL, &phy_reg);
> -	if (ret_val) {
> -		e1000e_enable_phy_retry(hw);
> -		hw->phy.ops.release(hw);
> -		goto out;
> +	if (hw->mac.type == e1000_pch_mtp) {
> +		ret_val = e1000e_force_smbus(hw);
> +		if (ret_val)
> +			e_dbg("Failed to force SMBUS over MTL system: %d\n", ret_val);
>   	}
> -	phy_reg |= CV_SMB_CTRL_FORCE_SMBUS;
> -	e1000_write_phy_reg_hv_locked(hw, CV_SMB_CTRL, phy_reg);
> -
> -	e1000e_enable_phy_retry(hw);
> -
> -	/* Force SMBus mode in MAC */
> -	mac_reg = er32(CTRL_EXT);
> -	mac_reg |= E1000_CTRL_EXT_FORCE_SMBUS;
> -	ew32(CTRL_EXT, mac_reg);
>   
>   	hw->phy.ops.release(hw);
>   out:

Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com> (A Contingent worker 
at Intel)