Date: Thu, 14 Dec 2023 13:37:12 +0000
From: "Jagielski, Jedrzej" <jedrzej.jagielski@...el.com>
To: Simon Horman <horms@...nel.org>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"Nguyen, Anthony L" <anthony.l.nguyen@...el.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
Subject: RE: [PATCH iwl-next v4 1/2] ixgbe: Refactor overtemp event handling

From: Simon Horman <horms@...nel.org> 
Sent: Thursday, December 14, 2023 10:56 AM

>On Tue, Dec 12, 2023 at 11:46:41AM +0100, Jedrzej Jagielski wrote:
>> Currently ixgbe driver is notified of overheating events
>> via internal IXGBE_ERR_OVERTEMP error code.
>> 
>> Change the approach for handle_lasi() to use freshly introduced
>> is_overtemp function parameter which set when such event occurs.
>> Change check_overtemp() to bool and return true if overtemp
>> event occurs.
>> 
>> Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@...el.com>
>> ---
>> v2: change aproach to use additional function parameter to notify when overheat
>> v4: change check_overtemp to bool
>> 
>> https://lore.kernel.org/netdev/20231208090055.303507-1-jedrzej.jagielski@intel.com/T/
>> ---
>
>Hi Jedrzej,
>
>I like where this patch-set is going.
>Please find some feedback from my side inline.

Hi Simon
thank you for the review.

>
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 19 ++++----
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_phy.c  | 26 ++++++-----
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h  |  2 +-
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_type.h |  4 +-
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c | 45 +++++++++++--------
>>  5 files changed, 54 insertions(+), 42 deletions(-)
>> 
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> index 227415d61efc..9bff614788a2 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> @@ -2756,7 +2756,7 @@ static void ixgbe_check_overtemp_subtask(struct ixgbe_adapter *adapter)
>>  {
>>  	struct ixgbe_hw *hw = &adapter->hw;
>>  	u32 eicr = adapter->interrupt_event;
>> -	s32 rc;
>> +	bool overtemp;
>>  
>>  	if (test_bit(__IXGBE_DOWN, &adapter->state))
>>  		return;
>> @@ -2790,14 +2790,15 @@ static void ixgbe_check_overtemp_subtask(struct ixgbe_adapter *adapter)
>>  		}
>>  
>>  		/* Check if this is not due to overtemp */
>> -		if (hw->phy.ops.check_overtemp(hw) != IXGBE_ERR_OVERTEMP)
>> +		overtemp = hw->phy.ops.check_overtemp(hw);
>> +		if (!overtemp)
>>  			return;
>
>I like the readability of the above, but FWIIW, I think it could
>also be slightly more compactly written as (completely untested!):
>
>		if (!hw->phy.ops.check_overtemp(hw))
>			return;

I decided to do that this way in order to improve readability,
but sure it can be changed.

>
>>  
>>  		break;
>>  	case IXGBE_DEV_ID_X550EM_A_1G_T:
>>  	case IXGBE_DEV_ID_X550EM_A_1G_T_L:
>> -		rc = hw->phy.ops.check_overtemp(hw);
>> -		if (rc != IXGBE_ERR_OVERTEMP)
>> +		overtemp = hw->phy.ops.check_overtemp(hw);
>> +		if (!overtemp)
>>  			return;
>>  		break;
>>  	default:
>> @@ -7938,7 +7939,7 @@ static void ixgbe_service_timer(struct timer_list *t)
>>  static void ixgbe_phy_interrupt_subtask(struct ixgbe_adapter *adapter)
>>  {
>>  	struct ixgbe_hw *hw = &adapter->hw;
>> -	u32 status;
>> +	bool overtemp;
>>  
>>  	if (!(adapter->flags2 & IXGBE_FLAG2_PHY_INTERRUPT))
>>  		return;
>> @@ -7948,11 +7949,9 @@ static void ixgbe_phy_interrupt_subtask(struct ixgbe_adapter *adapter)
>>  	if (!hw->phy.ops.handle_lasi)
>>  		return;
>>  
>> -	status = hw->phy.ops.handle_lasi(&adapter->hw);
>> -	if (status != IXGBE_ERR_OVERTEMP)
>> -		return;
>> -
>> -	e_crit(drv, "%s\n", ixgbe_overheat_msg);
>> +	hw->phy.ops.handle_lasi(&adapter->hw, &overtemp);
>
>Unless I am mistaken, the above can return an error. Should it be checked?

Since we are inside a void function we don't have many options to handle that.

I could be:
	err = hw->phy.ops.handle_lasi(&adapter->hw, &overtemp);
	if (err)
		return;
		
	if (!overtemp)
		return;
		
So i decided to shorten it just to 

	if (overtemp)
		...
		
Some solution instead of returning here is to log warning when error
encountered.		

>
>Or alternatively, as this seems to be the only call-site,
>could handle_lasi() return overtemp as a bool?

Actually handle_lasi() was designed to handle not only overtemp events
but also link status ones. When changing it to bool it would be
hard to differentiate them - then true only for overtemp case and false
when link change or any error? I am not sure if this is a good direction.

>
>> +	if (overtemp)
>> +		e_crit(drv, "%s\n", ixgbe_overheat_msg);
>>  }
>>  
>>  static void ixgbe_reset_subtask(struct ixgbe_adapter *adapter)
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.c
>> index ca31638c6fb8..343c3ca9b1c9 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.c
>> @@ -396,9 +396,10 @@ static enum ixgbe_phy_type ixgbe_get_phy_type_from_id(u32 phy_id)
>>   **/
>>  s32 ixgbe_reset_phy_generic(struct ixgbe_hw *hw)
>>  {
>> -	u32 i;
>> -	u16 ctrl = 0;
>>  	s32 status = 0;
>> +	bool overtemp;
>> +	u16 ctrl = 0;
>> +	u32 i;
>>  
>>  	if (hw->phy.type == ixgbe_phy_unknown)
>>  		status = ixgbe_identify_phy_generic(hw);
>> @@ -407,8 +408,8 @@ s32 ixgbe_reset_phy_generic(struct ixgbe_hw *hw)
>>  		return status;
>>  
>>  	/* Don't reset PHY if it's shut down due to overtemp. */
>> -	if (!hw->phy.reset_if_overtemp &&
>> -	    (IXGBE_ERR_OVERTEMP == hw->phy.ops.check_overtemp(hw)))
>> +	overtemp = hw->phy.ops.check_overtemp(hw);
>> +	if (!hw->phy.reset_if_overtemp && overtemp)
>>  		return 0;
>
>Previously check_overtemp() would only be called if reset_if_overtemp was
>false. Now it is called unconditionally. I'm not sure if it matters, but
>the check for reset_if_overtemp may have avoided some logic, including a
>call to hw->phy.ops.read_reg() in some cases.

Sure, the previous approach seems to be more efficient. Will be restored.

>
>I wonder if it would be nicer to go back to the previous logic.
>(completely untested!)
>
>	if (!hw->phy.reset_if_overtemp && hw->phy.ops.check_overtemp(hw))
>		return 0;
>
>>  
>>  	/* Blocked by MNG FW so bail */
>> @@ -2747,21 +2748,24 @@ static void ixgbe_i2c_bus_clear(struct ixgbe_hw *hw)
>>   *
>>   *  Checks if the LASI temp alarm status was triggered due to overtemp
>>   **/
>> -s32 ixgbe_tn_check_overtemp(struct ixgbe_hw *hw)
>> +bool ixgbe_tn_check_overtemp(struct ixgbe_hw *hw)
>>  {
>>  	u16 phy_data = 0;
>> +	u32 status;
>>  
>>  	if (hw->device_id != IXGBE_DEV_ID_82599_T3_LOM)
>> -		return 0;
>> +		return false;
>>  
>>  	/* Check that the LASI temp alarm status was triggered */
>> -	hw->phy.ops.read_reg(hw, IXGBE_TN_LASI_STATUS_REG,
>> -			     MDIO_MMD_PMAPMD, &phy_data);
>> +	status = hw->phy.ops.read_reg(hw, IXGBE_TN_LASI_STATUS_REG,
>> +				      MDIO_MMD_PMAPMD, &phy_data);
>> +	if (status)
>> +		return false;
>>  
>> -	if (!(phy_data & IXGBE_TN_LASI_STATUS_TEMP_ALARM))
>> -		return 0;
>> +	if (phy_data & IXGBE_TN_LASI_STATUS_TEMP_ALARM)
>> +		return true;
>>  
>> -	return IXGBE_ERR_OVERTEMP;
>> +	return false;
>
>Maybe (completely untested!):

I like it.

>
>	return !!(phy_data & IXGBE_TN_LASI_STATUS_TEMP_ALARM)
>
>>  }
>>  
>>  /** ixgbe_set_copper_phy_power - Control power for copper phy
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h
>> index 6544c4539c0d..ef72729d7c93 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h
>> @@ -155,7 +155,7 @@ s32 ixgbe_identify_sfp_module_generic(struct ixgbe_hw *hw);
>>  s32 ixgbe_get_sfp_init_sequence_offsets(struct ixgbe_hw *hw,
>>  					u16 *list_offset,
>>  					u16 *data_offset);
>> -s32 ixgbe_tn_check_overtemp(struct ixgbe_hw *hw);
>> +bool ixgbe_tn_check_overtemp(struct ixgbe_hw *hw);
>>  s32 ixgbe_read_i2c_byte_generic(struct ixgbe_hw *hw, u8 byte_offset,
>>  				u8 dev_addr, u8 *data);
>>  s32 ixgbe_read_i2c_byte_generic_unlocked(struct ixgbe_hw *hw, u8 byte_offset,
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
>> index 2b00db92b08f..91c9ecca4cb5 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_type.h
>> @@ -3509,10 +3509,10 @@ struct ixgbe_phy_operations {
>>  	s32 (*read_i2c_sff8472)(struct ixgbe_hw *, u8 , u8 *);
>>  	s32 (*read_i2c_eeprom)(struct ixgbe_hw *, u8 , u8 *);
>>  	s32 (*write_i2c_eeprom)(struct ixgbe_hw *, u8, u8);
>> -	s32 (*check_overtemp)(struct ixgbe_hw *);
>> +	bool (*check_overtemp)(struct ixgbe_hw *);
>>  	s32 (*set_phy_power)(struct ixgbe_hw *, bool on);
>>  	s32 (*enter_lplu)(struct ixgbe_hw *);
>> -	s32 (*handle_lasi)(struct ixgbe_hw *hw);
>> +	s32 (*handle_lasi)(struct ixgbe_hw *hw, bool *);
>
>I'm not sure of the history of this, or the nature of the other callbacks,
>but I think that usually int is used as the return type when standard error
>numbers are returned. I realise that is not strictly related to this patch,
>maybe it could be addressed at some point?

Sure, so it will be scheduled for the future.

>
>>  	s32 (*read_i2c_byte_unlocked)(struct ixgbe_hw *, u8 offset, u8 addr,
>>  				      u8 *value);
>>  	s32 (*write_i2c_byte_unlocked)(struct ixgbe_hw *, u8 offset, u8 addr,
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
>> index b3509b617a4e..59dd38dd8248 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_x550.c
>> @@ -600,8 +600,10 @@ static s32 ixgbe_setup_fw_link(struct ixgbe_hw *hw)
>>  	rc = ixgbe_fw_phy_activity(hw, FW_PHY_ACT_SETUP_LINK, &setup);
>>  	if (rc)
>>  		return rc;
>> +
>>  	if (setup[0] == FW_PHY_ACT_SETUP_LINK_RSP_DOWN)
>> -		return IXGBE_ERR_OVERTEMP;
>> +		return -EIO;
>> +
>>  	return 0;
>>  }
>>  
>> @@ -2367,18 +2369,21 @@ static s32 ixgbe_get_link_capabilities_X550em(struct ixgbe_hw *hw,
>>   * @hw: pointer to hardware structure
>>   * @lsc: pointer to boolean flag which indicates whether external Base T
>>   *	 PHY interrupt is lsc
>> + * @is_overtemp: indicate whether an overtemp event encountered
>>   *
>>   * Determime if external Base T PHY interrupt cause is high temperature
>>   * failure alarm or link status change.
>> - *
>> - * Return IXGBE_ERR_OVERTEMP if interrupt is high temperature
>> - * failure alarm, else return PHY access status.
>>   **/
>> -static s32 ixgbe_get_lasi_ext_t_x550em(struct ixgbe_hw *hw, bool *lsc)
>> +static s32 ixgbe_get_lasi_ext_t_x550em(struct ixgbe_hw *hw, bool *lsc,
>> +				       bool *is_overtemp)
>>  {
>>  	u32 status;
>>  	u16 reg;
>>  
>> +	if (!hw || !lsc || !is_overtemp)
>> +		return -EINVAL;
>
>I don't think this kind of defensive programming is appropriate
>in a kernel driver.

Ok, i wasn't sure. Just wanted to ensure we won't use is_overtemp if NULL.

>
>And unless I am mistaken, caller's don't check the return value of this
>function (or propagate to a caller which doesn't check it).

ixgbe_handle_lasi_ext_t_x550em() which is calling this function checks its
returned status.

>
>> +
>> +	*is_overtemp = false;
>>  	*lsc = false;
>>  
>>  	/* Vendor alarm triggered */
>> @@ -2410,7 +2415,8 @@ static s32 ixgbe_get_lasi_ext_t_x550em(struct ixgbe_hw *hw, bool *lsc)
>>  	if (reg & IXGBE_MDIO_GLOBAL_ALM_1_HI_TMP_FAIL) {
>>  		/* power down the PHY in case the PHY FW didn't already */
>>  		ixgbe_set_copper_phy_power(hw, false);
>> -		return IXGBE_ERR_OVERTEMP;
>> +		*is_overtemp = true;
>> +		return -EIO;
>>  	}
>>  	if (reg & IXGBE_MDIO_GLOBAL_ALM_1_DEV_FAULT) {
>>  		/*  device fault alarm triggered */
>> @@ -2424,7 +2430,8 @@ static s32 ixgbe_get_lasi_ext_t_x550em(struct ixgbe_hw *hw, bool *lsc)
>>  		if (reg == IXGBE_MDIO_GLOBAL_FAULT_MSG_HI_TMP) {
>>  			/* power down the PHY in case the PHY FW didn't */
>>  			ixgbe_set_copper_phy_power(hw, false);
>> -			return IXGBE_ERR_OVERTEMP;
>> +			*is_overtemp = true;
>> +			return -EIO;
>>  		}
>>  	}
>>  
>> @@ -2460,12 +2467,12 @@ static s32 ixgbe_get_lasi_ext_t_x550em(struct ixgbe_hw *hw, bool *lsc)
>>   **/
>>  static s32 ixgbe_enable_lasi_ext_t_x550em(struct ixgbe_hw *hw)
>>  {
>> +	bool lsc, overtemp;
>>  	u32 status;
>>  	u16 reg;
>> -	bool lsc;
>>  
>>  	/* Clear interrupt flags */
>> -	status = ixgbe_get_lasi_ext_t_x550em(hw, &lsc);
>> +	status = ixgbe_get_lasi_ext_t_x550em(hw, &lsc, &overtemp);
>>  
>>  	/* Enable link status change alarm */
>>  
>> @@ -2544,21 +2551,23 @@ static s32 ixgbe_enable_lasi_ext_t_x550em(struct ixgbe_hw *hw)
>>  /**
>>   * ixgbe_handle_lasi_ext_t_x550em - Handle external Base T PHY interrupt
>>   * @hw: pointer to hardware structure
>> + * @is_overtemp: indicate whether an overtemp event encountered
>>   *
>>   * Handle external Base T PHY interrupt. If high temperature
>>   * failure alarm then return error, else if link status change
>>   * then setup internal/external PHY link
>> - *
>> - * Return IXGBE_ERR_OVERTEMP if interrupt is high temperature
>> - * failure alarm, else return PHY access status.
>>   **/
>> -static s32 ixgbe_handle_lasi_ext_t_x550em(struct ixgbe_hw *hw)
>> +static s32 ixgbe_handle_lasi_ext_t_x550em(struct ixgbe_hw *hw,
>> +					  bool *is_overtemp)
>>  {
>>  	struct ixgbe_phy_info *phy = &hw->phy;
>>  	bool lsc;
>>  	u32 status;
>>  
>> -	status = ixgbe_get_lasi_ext_t_x550em(hw, &lsc);
>> +	if (!hw || !is_overtemp)
>> +		return -EINVAL;
>
>Ditto.
>
>> +
>> +	status = ixgbe_get_lasi_ext_t_x550em(hw, &lsc, is_overtemp);
>>  	if (status)
>>  		return status;
>>  
>> @@ -3186,20 +3195,20 @@ static s32 ixgbe_reset_phy_fw(struct ixgbe_hw *hw)
>>   * ixgbe_check_overtemp_fw - Check firmware-controlled PHYs for overtemp
>>   * @hw: pointer to hardware structure
>>   */
>> -static s32 ixgbe_check_overtemp_fw(struct ixgbe_hw *hw)
>> +static bool ixgbe_check_overtemp_fw(struct ixgbe_hw *hw)
>>  {
>>  	u32 store[FW_PHY_ACT_DATA_COUNT] = { 0 };
>>  	s32 rc;
>>  
>>  	rc = ixgbe_fw_phy_activity(hw, FW_PHY_ACT_GET_LINK_INFO, &store);
>>  	if (rc)
>> -		return rc;
>> +		return false;
>>  
>>  	if (store[0] & FW_PHY_ACT_GET_LINK_INFO_TEMP) {
>>  		ixgbe_shutdown_fw_phy(hw);
>> -		return IXGBE_ERR_OVERTEMP;
>> +		return true;
>>  	}
>> -	return 0;
>> +	return false;
>>  }
>>  
>>  /**
>> -- 
>> 2.31.1
>>

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