| Message ID | 20241106184722.17230-1-christopher.s.hall@intel.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | igc: Fix PTM timeout | expand |
Hi Chris, On Nov 6 18:47, Christopher S M Hall wrote: > There have been sporadic reports of PTM timeouts using i225/i226 devices > > These timeouts have been root caused to: > > 1) Manipulating the PTM status register while PTM is enabled and triggered > 2) The hardware retrying too quickly when an inappropriate response is > received from the upstream device > > The issue can be reproduced with the following: > > $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m > > Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to > quickly reproduce the issue. > > PHC2SYS exits with: > > "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction > fails > > Additional problem description tested by: > Corinna Vinschen <vinschen@redhat.com> > > This patch also fixes a hang in igc_probe() when loading the igc > driver in the kdump kernel on systems supporting PTM. > > The igc driver running in the base kernel enables PTM trigger in > igc_probe(). Therefore the driver is always in PTM trigger mode, > except in brief periods when manually triggering a PTM cycle. > > When a crash occurs, the NIC is reset while PTM trigger is enabled. > Due to a hardware problem, the NIC is subsequently in a bad busmaster > state and doesn't handle register reads/writes. When running > igc_probe() in the kdump kernel, the first register access to a NIC > register hangs driver probing and ultimately breaks kdump. > > With this patch, igc has PTM trigger disabled most of the time, > and the trigger is only enabled for very brief (10 - 100 us) periods > when manually triggering a PTM cycle. Chances that a crash occurs > during a PTM trigger are not zero, but extremly reduced. The patchset looks good to me, but I don't see that this description will make it into the commit message of patch 1. Was that intended? Other than that... Reviewed-by: Corinna Vinschen <vinschen@redhat.com> Thanks, Corinna
There have been sporadic reports of PTM timeouts using i225/i226 devices These timeouts have been root caused to: 1) Manipulating the PTM status register while PTM is enabled and triggered 2) The hardware retrying too quickly when an inappropriate response is received from the upstream device The issue can be reproduced with the following: $ sudo phc2sys -R 1000 -O 0 -i tsn0 -m Note: 1000 Hz (-R 1000) is unrealistically large, but provides a way to quickly reproduce the issue. PHC2SYS exits with: "ioctl PTP_OFFSET_PRECISE: Connection timed out" when the PTM transaction fails Additional problem description tested by: Corinna Vinschen <vinschen@redhat.com> This patch also fixes a hang in igc_probe() when loading the igc driver in the kdump kernel on systems supporting PTM. The igc driver running in the base kernel enables PTM trigger in igc_probe(). Therefore the driver is always in PTM trigger mode, except in brief periods when manually triggering a PTM cycle. When a crash occurs, the NIC is reset while PTM trigger is enabled. Due to a hardware problem, the NIC is subsequently in a bad busmaster state and doesn't handle register reads/writes. When running igc_probe() in the kdump kernel, the first register access to a NIC register hangs driver probing and ultimately breaks kdump. With this patch, igc has PTM trigger disabled most of the time, and the trigger is only enabled for very brief (10 - 100 us) periods when manually triggering a PTM cycle. Chances that a crash occurs during a PTM trigger are not zero, but extremly reduced. Changelog: v1 -> v2: -Removed patch modifying PTM retry loop count -Moved PTM mutex initialization from igc_reset() to igc_ptp_init() called once in igc_probe() v2 -> v3: -Added mutex_destroy() to clean up PTM lock -Added missing checks for PTP enabled flag called from igc_main.c -Cleanup PTP module if probe fails -Wrap all access to PTM registers with PTM lock/unlock Christopher S M Hall (6): igc: Ensure the PTM cycle is reliably triggered igc: Lengthen the hardware retry time to prevent timeouts igc: Move ktime snapshot into PTM retry loop igc: Handle the IGC_PTP_ENABLED flag correctly igc: Cleanup PTP module if probe fails igc: Add lock preventing multiple simultaneous PTM transactions drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_defines.h | 3 +- drivers/net/ethernet/intel/igc/igc_main.c | 1 + drivers/net/ethernet/intel/igc/igc_ptp.c | 113 ++++++++++++------- 4 files changed, 78 insertions(+), 40 deletions(-)