[WIP] Remove EtherCAT DC related code except config parsing

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

Original prompt

Objective

Remove all EtherCAT DC (Distributed Clock) related code from the codebase, except for the refClockSyncCycles config parsing in lcec_conf.c (and its corresponding field in the LCEC_CONF_MASTER_T struct in conf.h/lcec_conf.h).

This is on the dc-rewrite branch. The branch has a reorganized source structure compared to master (e.g. conf.h instead of lcec_conf.h, pal/pal.h, etc).

What to KEEP

1. refClockSyncCycles field in LCEC_CONF_MASTER_T struct (in conf.h or lcec_conf.h)
2. refClockSyncCycles XML attribute parsing in lcec_conf.c / parseMasterAttrs (the code that parses refClockSyncCycles from XML config)
3. sync_ref_cycles field in lcec_master_t struct (in src/lcec.h) - keep the field itself as it stores the parsed value
4. master->sync_ref_cycles = master_conf->refClockSyncCycles; assignment in lcec_main.c - keep this line that copies the config value

What to REMOVE

In src/lcec.h:

1. lcec_slave_dc_t struct - the entire typedef struct with assignActivate, sync0Cycle, sync0Shift, sync1Cycle, sync1Shift fields
2. lcec_slave_dc_t *dc_conf; field from lcec_slave_t struct
3. DC-related fields in lcec_master_t within #ifdef RTAPI_TASK_PLL_SUPPORT block:
   • uint64_t dc_ref;
   • uint32_t app_time_last;
   • int dc_time_valid_last;
4. sync_ref_cnt field from lcec_master_t
5. PLL-related fields in lcec_master_data_t within #ifdef RTAPI_TASK_PLL_SUPPORT block:
   • hal_s32_t *pll_err;
   • hal_s32_t *pll_out;
   • hal_u32_t pll_step;
   • hal_u32_t pll_max_err;
   • hal_u32_t *pll_reset_cnt;

In src/lcec_main.c:

1. Slave DC configuration - Remove ecrt_slave_config_dc() call and the surrounding code/log messages that configure DC for slaves using slave->dc_conf
2. All sync_ref_cnt / sync_ref_cycles usage in the write function - the block that calls ecrt_master_sync_reference_clock() with the ref counter
3. All #ifdef RTAPI_TASK_PLL_SUPPORT blocks dealing with DC sync:
   • The PLL reference time acquisition (rtapi_task_pll_get_reference())
   • The DC-aware application time calculation (master->dc_ref += period; app_time = ...)
   • The DC reference clock time retrieval (ecrt_master_reference_clock_time())
   • The BANG-BANG PLL controller code
   • rtapi_task_pll_set_correction() calls
   • master->dc_time_valid_last usage
   • master->app_time_last usage
4. ecrt_master_sync_slave_clocks() call
5. ecrt_master_sync_reference_clock() call
6. DC-related initialization code - the block that initializes dc_time_valid_last, dc_ref, handles sync_ref_cycles sign for app_time_base adjustment
7. PLL HAL pin exports - any code that creates HAL pins for pll_err, pll_out, pll_step, pll_max_err, pll_reset_cnt
8. Simplify the application time computation to just: app_time = master->app_time_base + rtapi_get_time(); (remove all the conditional #ifdef variants)

In config files (conf.h / lcec_conf.h):

1. LCEC_CONF_DC_T struct - the entire typedef struct with DC configuration fields
2. lcecConfTypeDc enum value (if present in LCEC_CONF_TYPE_T)

In lcec_conf.c:

1. parseDcConfAttrs function or equivalent DC config parsing function
2. DC XML element handling - the XML parser state/transition that handles <dcConf> elements
3. Any DC-related output buffer writes for LCEC_CONF_DC_T

In lcec_main.c config processing:

1. case lcecConfTypeDc: block that processes DC configuration from shared memory and allocates/assigns slave->dc_conf

Important Notes

• The application time computation should be simplified. Remove all the #ifdef RTAPI_TASK_PLL_SUPPORT conditional branches and just use the simple computation: app_time = master->app_time_base + rtapi_get_time();
• Similarly, app_time_base initialization should be simplified to just: master->app_time_base -= rtapi_get_time(); without any conditional branches
• ecrt_master_application_time() should still be called with the simplified app_time
• ecrt_domain_queue(), ecrt_master_send() and the mutex handling should remain
• The write function structure (processing slaves, sending process data) should remain intact
• Keep master->app_time_period as it may be used elsewhere
• Make sure no dangling references remain to removed types/fields

This pull request was created from Copilot chat.

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