Fix hardcoded lane masks when applying loopbacks#686
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Signed-off-by: Abhi Singh <abhi@nexthop.ai>
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prgeor
reviewed
Jun 11, 2026
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| def _get_active_appsel_descriptor(self): | ||
| ''' | ||
| Returns the application-advertisement descriptor for the currently | ||
| active AppSel on host lane 1. | ||
|
|
||
| Raises RuntimeError if the active AppSel cannot be determined -- | ||
| callers must not silently fall back to the default-application | ||
| descriptor, since that defeats the purpose of resolving the | ||
| runtime-configured application. | ||
| ''' | ||
| if self.is_flat_memory(): | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'module reports flat memory (page 11h unavailable)') | ||
|
|
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| lane1_field = "%s%d" % (consts.ACTIVE_APSEL_HOSTLANE, 1) | ||
| active_apsel = self.xcvr_eeprom.read(lane1_field) | ||
| if not active_apsel: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'read of %s returned %r' % (lane1_field, active_apsel)) | ||
|
|
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| appl_advt = self.get_application_advertisement() | ||
| descriptor = appl_advt.get(active_apsel) | ||
| if not descriptor: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'AppSel %d has no entry in application advertisement %r' | ||
| % (active_apsel, appl_advt)) | ||
|
|
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| return active_apsel, descriptor | ||
|
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| def get_active_appsel_host_lane_count(self): | ||
| ''' | ||
| Returns the host lane count for the currently active application. | ||
|
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| Reads the applied AppSel code from the DataPath Configuration | ||
| (Page 11h) and looks up the corresponding application descriptor. | ||
| Raises RuntimeError if the active AppSel cannot be determined or | ||
| the descriptor lacks a host_lane_count | ||
| ''' | ||
| active_apsel, descriptor = self._get_active_appsel_descriptor() | ||
| if 'host_lane_count' not in descriptor: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel host lane count: ' | ||
| 'AppSel %d descriptor %r has no host_lane_count' | ||
| % (active_apsel, descriptor)) | ||
| return descriptor['host_lane_count'] | ||
|
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| def get_active_appsel_media_lane_count(self): | ||
| ''' | ||
| Returns the media lane count for the currently active application. | ||
|
|
Collaborator
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@abhi-nexthop we don't have existing APIs for these? cc @mihirpat1
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Pull request overview
This PR updates the CMIS transceiver loopback implementation to avoid using a hardcoded 0xFF lane mask by deriving the “all lanes” mask from the currently active AppSel’s host/media lane counts, improving compatibility with 1-lane / smaller-lane-count modules.
Changes:
- Add APIs to resolve the active AppSel descriptor and fetch active host/media lane counts from Page 11h + application advertisement.
- Use the derived “all lanes” mask instead of
0xFFfor loopback operations (notably when disabling all loopbacks vialoopback_mode == 'none'). - Extend unit tests to cover the new active-lane-count APIs and updated loopback behaviors.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 9 comments.
| File | Description |
|---|---|
| tests/sonic_xcvr/test_cmis.py | Adds tests for active AppSel lane count helpers; updates loopback tests to account for derived masks. |
| sonic_platform_base/sonic_xcvr/api/public/cmis.py | Introduces active AppSel lane-count helpers; replaces hardcoded lane masks in loopback paths; minor boolean conversion change for media loopback getters. |
Comment on lines
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| all_lanes_mask = (1 << self.get_active_appsel_host_lane_count()) - 1 | ||
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane host input loopback is not supported, lane_mask:%#x', lane_mask) | ||
| return False |
Comment on lines
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| all_lanes_mask = (1 << self.get_active_appsel_host_lane_count()) - 1 | ||
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane host output loopback is not supported, lane_mask:%#x', lane_mask) | ||
| return False |
Comment on lines
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| all_lanes_mask = (1 << self.get_active_appsel_media_lane_count()) - 1 | ||
| if loopback_capability['per_lane_media_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane media input loopback is not supported, lane_mask:%#x', lane_mask) | ||
| return False |
Comment on lines
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| all_lanes_mask = (1 << self.get_active_appsel_media_lane_count()) - 1 | ||
| if loopback_capability['per_lane_media_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane media output loopback is not supported, lane_mask:%#x', lane_mask) | ||
| return False |
Comment on lines
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| if loopback_mode == 'none': | ||
| host_all_lanes_mask = (1 << self.get_active_appsel_host_lane_count()) - 1 | ||
| media_all_lanes_mask = (1 << self.get_active_appsel_media_lane_count()) - 1 | ||
| return all([ | ||
| self.set_host_input_loopback(0xff, False), | ||
| self.set_host_output_loopback(0xff, False), | ||
| self.set_media_input_loopback(0xff, False), | ||
| self.set_media_output_loopback(0xff, False) | ||
| self.set_host_input_loopback(host_all_lanes_mask, False), | ||
| self.set_host_output_loopback(host_all_lanes_mask, False), | ||
| self.set_media_input_loopback(media_all_lanes_mask, False), | ||
| self.set_media_output_loopback(media_all_lanes_mask, False) | ||
| ]) |
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| def _get_active_appsel_descriptor(self): | ||
| ''' | ||
| Returns the application-advertisement descriptor for the currently | ||
| active AppSel on host lane 1. | ||
|
|
||
| Raises RuntimeError if the active AppSel cannot be determined -- | ||
| callers must not silently fall back to the default-application | ||
| descriptor, since that defeats the purpose of resolving the | ||
| runtime-configured application. | ||
| ''' | ||
| if self.is_flat_memory(): | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'module reports flat memory (page 11h unavailable)') | ||
|
|
||
| lane1_field = "%s%d" % (consts.ACTIVE_APSEL_HOSTLANE, 1) | ||
| active_apsel = self.xcvr_eeprom.read(lane1_field) | ||
| if not active_apsel: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'read of %s returned %r' % (lane1_field, active_apsel)) | ||
|
|
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| appl_advt = self.get_application_advertisement() | ||
| descriptor = appl_advt.get(active_apsel) | ||
| if not descriptor: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel descriptor: ' | ||
| 'AppSel %d has no entry in application advertisement %r' | ||
| % (active_apsel, appl_advt)) | ||
|
|
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| return active_apsel, descriptor | ||
|
|
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| def get_active_appsel_host_lane_count(self): | ||
| ''' | ||
| Returns the host lane count for the currently active application. | ||
|
|
||
| Reads the applied AppSel code from the DataPath Configuration | ||
| (Page 11h) and looks up the corresponding application descriptor. | ||
| Raises RuntimeError if the active AppSel cannot be determined or | ||
| the descriptor lacks a host_lane_count | ||
| ''' | ||
| active_apsel, descriptor = self._get_active_appsel_descriptor() | ||
| if 'host_lane_count' not in descriptor: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel host lane count: ' | ||
| 'AppSel %d descriptor %r has no host_lane_count' | ||
| % (active_apsel, descriptor)) | ||
| return descriptor['host_lane_count'] | ||
|
|
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| def get_active_appsel_media_lane_count(self): | ||
| ''' | ||
| Returns the media lane count for the currently active application. | ||
|
|
||
| Reads the applied AppSel code from the DataPath Configuration | ||
| (Page 11h) and looks up the corresponding application descriptor. | ||
| Raises RuntimeError if the active AppSel cannot be determined or | ||
| the descriptor lacks a media_lane_count | ||
| ''' | ||
| active_apsel, descriptor = self._get_active_appsel_descriptor() | ||
| if 'media_lane_count' not in descriptor: | ||
| raise RuntimeError( | ||
| 'Cannot determine active AppSel media lane count: ' | ||
| 'AppSel %d descriptor %r has no media_lane_count' | ||
| % (active_apsel, descriptor)) | ||
| return descriptor['media_lane_count'] |
Comment on lines
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| self.api.set_media_output_loopback = MagicMock() | ||
| self.api.set_media_output_loopback.return_value = mock_response | ||
| self.api.get_active_appsel_host_lane_count = MagicMock(return_value=8) | ||
| self.api.get_active_appsel_media_lane_count = MagicMock(return_value=8) | ||
| result = self.api.set_loopback_mode(input_param[0], input_param[1]) | ||
| assert result == expected |
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != 0xff: | ||
| all_lanes_mask = (1 << self.get_active_appsel_host_lane_count()) - 1 | ||
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane host input loopback is not supported, lane_mask:%#x', lane_mask) |
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != 0xff: | ||
| all_lanes_mask = (1 << self.get_active_appsel_host_lane_count()) - 1 | ||
| if loopback_capability['per_lane_host_loopback_supported'] is False and lane_mask != all_lanes_mask: | ||
| logger.error('Per-lane host output loopback is not supported, lane_mask:%#x', lane_mask) |
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Description
Certain transceivers expect exact lane masks for the active appsel when setting Media Side and Host side loopbacks respectively.
Currently, we have them hardcoded as 0xFF which works on certain transceivers but not others. On a 1 media lane transceiver, trying to disable loopback on it with 0xFF might fail depending on the device. We noticed this on several transceivers
Motivation and Context
How Has This Been Tested?
Tested on INPHI CORP IN-Q3JZ1-TC-M1 and Acacia DP04QSDD-E20-001
Acacia works with and without the fix
IN-Q3JZ1-TC-M1 fails to set any kind of media loopback without the fix
Additional Information (Optional)