Faizal Rahim faizal.abdul.rahim@linux.intel.com writes:
When user issues these cmds:
- Either a) or b) a) mqprio with hardware offload disabled b) taprio with txtime-assist feature enabled
- etf
- tc qdisc delete
- taprio with base time in the past
At step 4, qbv_config_change_errors wrongly increased by 1.
Excerpt from IEEE 802.1Q-2018 8.6.9.3.1: "If AdminBaseTime specifies a time in the past, and the current schedule is running, then: Increment ConfigChangeError counter"
qbv_config_change_errors should only increase if base time is in the past and no taprio is active. In user perspective, taprio was not active when first triggered at step 4. However, i225/6 reuses qbv for etf, so qbv is enabled with a dummy schedule at step 2 where it enters igc_tsn_enable_offload() and qbv_count got incremented to 1. At step 4, it enters igc_tsn_enable_offload() again, qbv_count is incremented to 2. Because taprio is running, tc_setup_type is TC_SETUP_QDISC_ETF and qbv_count > 1, qbv_config_change_errors value got incremented.
This issue happens due to reliance on qbv_count field where a non-zero value indicates that taprio is running. But qbv_count increases regardless if taprio is triggered by user or by other tsn feature. It does not align with qbv_config_change_errors expectation where it is only concerned with taprio triggered by user.
Fixing this by relocating the qbv_config_change_errors logic to igc_save_qbv_schedule(), eliminating reliance on qbv_count and its inaccuracies from i225/6's multiple uses of qbv feature for other TSN features.
The new function created: igc_tsn_is_taprio_activated_by_user() uses taprio_offload_enable field to indicate that the current running taprio was triggered by user, instead of triggered by non-qbv feature like etf.
Fixes: ae4fe4698300 ("igc: Add qbv_config_change_errors counter") Signed-off-by: Faizal Rahim faizal.abdul.rahim@linux.intel.com Reviewed-by: Simon Horman horms@kernel.org
Looks good:
Acked-by: Vinicius Costa Gomes vinicius.gomes@intel.com
Cheers,