RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and linking on hotplug

[Jeff Daly <jeffd@silicom-usa.com>]

> -----Original Message-----
> From: Wang, Haiyue <haiyue.wang@intel.com>
> Sent: Monday, April 18, 2022 10:05 PM
> To: Jeff Daly <jeffd@silicom-usa.com>; dev@dpdk.org
> Cc: stable@dpdk.org; Yang, Qiming <qiming.yang@intel.com>
> Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and linking on
> hotplug
> 
> Caution: This is an external email. Please take care when clicking links or
> opening attachments.
> 
> 
> > -----Original Message-----
> > From: Jeff Daly <jeffd@silicom-usa.com>
> > Sent: Tuesday, April 19, 2022 05:55
> > To: Wang, Haiyue <haiyue.wang@intel.com>; dev@dpdk.org
> > Cc: stable@dpdk.org
> > Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and linking
> > on hotplug
> >
> >
> >
> > > -----Original Message-----
> > > From: Wang, Haiyue <haiyue.wang@intel.com>
> > > Sent: Thursday, April 14, 2022 8:11 AM
> > > To: Jeff Daly <jeffd@silicom-usa.com>; dev@dpdk.org
> > > Cc: stable@dpdk.org
> > > Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and linking
> > > on hotplug
> > >
> > > Caution: This is an external email. Please take care when clicking
> > > links or opening attachments.
> > >
> > >
> > > > -----Original Message-----
> > > > From: Jeff Daly <jeffd@silicom-usa.com>
> > > > Sent: Thursday, April 14, 2022 18:41
> > > > To: Wang, Haiyue <haiyue.wang@intel.com>; dev@dpdk.org
> > > > Cc: stable@dpdk.org
> > > > Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and
> > > > linking on hotplug
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Wang, Haiyue <haiyue.wang@intel.com>
> > > > > Sent: Wednesday, April 13, 2022 11:00 PM
> > > > > To: Jeff Daly <jeffd@silicom-usa.com>; dev@dpdk.org
> > > > > Cc: stable@dpdk.org; Stephen Douthit <stephend@silicom-usa.com>
> > > > > Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and
> > > > > linking on hotplug
> > > > >
> > > > > Caution: This is an external email. Please take care when
> > > > > clicking links or opening attachments.
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Wang, Haiyue
> > > > > > Sent: Thursday, April 14, 2022 10:49
> > > > > > To: Jeff Daly <jeffd@silicom-usa.com>; dev@dpdk.org
> > > > > > Cc: stable@dpdk.org; Stephen Douthit
> > > > > > <stephend@silicom-usa.com>
> > > > > > Subject: RE: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and
> > > > > > linking on hotplug
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Jeff Daly <jeffd@silicom-usa.com>
> > > > > > > Sent: Wednesday, April 13, 2022 01:42
> > > > > > > To: dev@dpdk.org
> > > > > > > Cc: stable@dpdk.org; Stephen Douthit
> > > > > > > <stephend@silicom-usa.com>; Wang, Haiyue
> > > > > > > <haiyue.wang@intel.com>
> > > > > > > Subject: [PATCH v6 2/2] net/ixgbe: Fix SFP detection and
> > > > > > > linking on hotplug
> > > > > > >
> > > > > > > Currently the ixgbe driver does not ID any SFP except for
> > > > > > > the first one plugged in. This can lead to no-link, or
> > > > > > > incorrect speed
> > > conditions.
> > > > > > >
> > > > > > > For example:
> > > > > > >
> > > > > > > * If link is initially established with a 1G SFP, and later
> > > > > > > a 1G/10G multispeed part is later installed, then the MAC
> > > > > > > link setup functions are never called to change from
> > > > > > > 1000BASE-X to 10GBASE-R mode, and the link stays running at the
> slower rate.
> > > > > > >
> > > > > > > * If link is initially established with a 1G SFP, and later
> > > > > > > a 10G only module is later installed, no link is
> > > > > > > established, since we are still trasnsmitting in 1000BASE-X
> > > > > > > mode to a 10GBASE-R
> > > only partner.
> > > > > > >
> > > > > > > Refactor the SFP ID/setup, and link setup code, to more
> > > > > > > closely match the flow of the mainline kernel driver which
> > > > > > > does not have these issues.  In that driver a service task
> > > > > > > runs periodically to handle these operations based on bit
> > > > > > > flags that have been set (usually via interrupt or userspace
> > > > > > > request), and then get cleared once the requested subtask has
> been completed.
> > > > > > >
> > > > > > > Fixes: af75078fece ("first public release")
> > > > > > > Cc: stable@dpdk.org
> > > > > > >
> > > > > > > Signed-off-by: Stephen Douthit <stephend@silicom-usa.com>
> > > > > > > Signed-off-by: Jeff Daly <jeffd@silicom-usa.com>
> > > > > > > ---
> > > > > > >  drivers/net/ixgbe/ixgbe_ethdev.c | 533
> > > > > > > +++++++++++++++++++++++--------
> > > > > > > +++++++++++++++++++++++drivers/net/ixgbe/ixgbe_ethdev.h |
> > > > > > > 14 +-
> > > > > > >  2 files changed, 410 insertions(+), 137 deletions(-)
> > > > > > >
> > > > > >
> > > > > >
> > > > > > >
> > > > > > >  struct ixgbe_stat_mapping_registers { @@ -510,7 +509,7 @@
> > > > > > > struct ixgbe_adapter {
> > > > > > >     uint8_t pflink_fullchk;
> > > > > > >     uint8_t mac_ctrl_frame_fwd;
> > > > > > >     rte_atomic32_t link_thread_running;
> > > > > > > -   pthread_t link_thread_tid;
> > > > > > > +   pthread_t service_thread_tid;
> > > > > >
> > > > > > No need to rename this variable,
> > > > >
> > > > > Let's do link related service now, so we can keep it, I missed
> > > > > to add my comment. ;-)
> > > > >
> > > >
> > > > I don't understand this reply, are you still asking to rework the
> > > > patch or
> > > not?
> > > >
> > >
> > > Different thing.
> > >
> > > 1. This var can be kept to trace the created thread. (change less code to
> keep
> > >    the patch clean.)
> > > 2. Yes, two patches.
> > >
> >
> > ok, I guess I'm just being thick-headed here, but I still don't
> > understand why you are saying it should be split into
> > 2 patches.  if I understand *what* you are asking, you're saying make
> > the original thread periodic to continuously
> 
> Well, ...
> 
> Your patch merges the original 'ixgbe_setup_link' task into one, this will
> make us hard to review the whole design. So what I said
> is: firstly, let's change the thread to a service thread to handle the
> 'ixgbe_setup_link' subtask firstly. Which is 'ixgbe_link_service'
> in your whole patch.
> 

still not 100%, are you suggesting that the original ixgbe_dev_setup_link_thread_handler()
which currently is not periodic and only really calls ixgbe_setup_link() be changed to be a 
periodic task that essentially does what the patch's ixgbe_link_service() function does which
would only be checking whether link config is needed and if so calls ixgbe_setup_link() as 
before?

if I'm following the code correctly, it ends up going down to ixgbe_check_mac_link_generic()
which looks at SDP0 (in the case of needing xtalk fix) which incorrectly will set sfp_cage_full
when in fact the PRESENT# signal (or MOD_ABS#) is active low.  the code is extremely convoluted
in it's effort to be smart so I may be missing something, but I *believe* that what we end up
with is completely unnecessary probing of i2c busses looking for SFPs that don't exist.  even when
making it periodic, I don't think it's going to end up with working code.

> Small patch is good for us to review, and try to do one thing.
> 
> Hope this time, I can make myself clear. ;-)
> 
> > do ixgbe_link_setup() ?  I believe the problem with the setup is that
> > the sfp_type is only detected once at initialization time and if
> > nothing is in the cage then the code just returns IXGBE_SUCCESS, in
> > which case making this task periodic is useless.  the whole issue of
> > hotplug is only addressed by the entire patch which
> > 1) makes the
> > task periodic, 2) changes the actions of the task to look for whether
> > the cage has something in it and whether its been changed and needs to
> > be configured again.
> >
> >
> > > > > > we can separate this patch as least into two patches:
> > > > >
> > > > >
> > > > > >
> > > > > > 1st, change the thread handle
> 'ixgbe_dev_setup_link_thread_handler'
> > > > > > from
> > > > > >
> > > > > > run-once to as periodical, to handle the original issue.
> > > > > >
> > > > > > The name 'ixgbe_dev_setup_link_thread_handler' may be not
> > > > > > suitable now, as it is a service thread.
> > > > > >
> > > > > > We can change it to "'ixgbe_link_service_thread_handler'" to
> > > > > > reflect the change purpose.
> > > > > >
> > > > > > 2nd, add the SFP hotplug in this patch.
> > > > > >
> > > > > >
> > > > > >
> > > > > > >  };
> > > > > > >
> > > > > > > --
> > > > > > > 2.25.1