Re: [dpdk-dev] [PATCH v3 1/2] net/ixgbe: fix x550 code to handle unidentified PHY

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Chas Williams [mailto:3chas3@gmail.com]
> Sent: Monday, November 5, 2018 11:19 AM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Luca Boccassi <bluca@debian.org>;
> dev@dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; stable@dpdk.org
> Subject: Re: [PATCH v3 1/2] net/ixgbe: fix x550 code to handle unidentified
> PHY
> 
> 
> 
> On 11/05/2018 12:41 PM, Zhang, Qi Z wrote:
> >
> >
> >> -----Original Message-----
> >> From: Luca Boccassi [mailto:bluca@debian.org]
> >> Sent: Friday, November 2, 2018 8:19 AM
> >> To: dev@dpdk.org
> >> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Ananyev, Konstantin
> >> <konstantin.ananyev@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>;
> >> 3chas3@gmail.com; Luca Boccassi <bluca@debian.org>; stable@dpdk.org
> >> Subject: [PATCH v3 1/2] net/ixgbe: fix x550 code to handle
> >> unidentified PHY
> >>
> >> ixgbe_identify_sfp_module_X550em() was missing the code to handle
> >> unidentified PHY that has been there in 82599 so it was not able to
> >> complete initialization of ixgbe sequence if no sfp plugged in.
> >> Port it over to return an appropriate type and complete init sequence
> >> properly.
> >>
> >> Fixes: d2e72774e58c ("ixgbe/base: support X550")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Luca Boccassi <bluca@debian.org>
> >> ---
> >> v2: refresh to remove merge conflict with master
> >> v3: coalesce fix into ixgbe_identify_sfp_module_X550em to avoid
> >>      code duplication, improve comment
> >>
> >>   drivers/net/ixgbe/base/ixgbe_x550.c | 6 ++++++
> >>   1 file changed, 6 insertions(+)
> >>
> >> diff --git a/drivers/net/ixgbe/base/ixgbe_x550.c
> >> b/drivers/net/ixgbe/base/ixgbe_x550.c
> >> index f7b98af52..a88d5c86a 100644
> >> --- a/drivers/net/ixgbe/base/ixgbe_x550.c
> >> +++ b/drivers/net/ixgbe/base/ixgbe_x550.c
> >> @@ -1561,6 +1561,12 @@ s32
> ixgbe_identify_sfp_module_X550em(struct
> >> ixgbe_hw *hw)
> >>
> >>   	status = ixgbe_identify_module_generic(hw);
> >>
> >> +	/* Set PHY type none if no PHY detected to allow init without SFP */
> >> +	if (hw->phy.type == ixgbe_phy_unknown) {
> >> +		hw->phy.type = ixgbe_phy_none;
> >
> > Set PHY type to none for a device that does have PHY looks weird.
> > does ixgeb_phy_generic works here?
> 
> Yes, it does seem strange but that's what ixgbe_identify_sfp_module_generic
> seems to do:
> 
> 	err_read_i2c_eeprom:
> 		hw->phy.sfp_type = ixgbe_sfp_type_not_present;
> 		if (hw->phy.type != ixgbe_phy_nl) {
> 			hw->phy.id = 0;
> 			hw->phy.type = ixgbe_phy_unknown;
> 		}
> 
> The QSFP version a little more forceful:
> 
> 	err_read_i2c_eeprom:
> 		hw->phy.sfp_type = ixgbe_sfp_type_not_present;
> 		hw->phy.id = 0;
> 		hw->phy.type = ixgbe_phy_unknown;
> 
> If we go forward without setting the phy_type to none, we will eventually run
> into issues calling other phy routines.
> 
> So should a lack of SFP, reset the PHY type? It's hazy because the difference
> between PHY and SFP isn't that clear to me here.

I'm not sure that's the same case:).
Just feel that it's better to handle ixgbe_phy_unknown directly for some device id as a special case than just replace it to ixgbe_phy_none to cheat the check path, since that rely on we never change the way to handle ixgbe_phy_none.

So still have the question?
What is the failure if you go with ixgbe_phy_unknown?
Is that possible to work around this like
if (phy_type == ixgbe_phy_unknown && dev_id == xxxx)
	...

> 
> > Where is failure you met with ixgbe_phy_unknown?
> >
> >> +		return IXGBE_SUCCESS;
> >> +	}
> >> +
> >>   	if (status != IXGBE_SUCCESS)
> >>   		return status;
> >>
> >> --
> >> 2.19.1
> >