[GitHub] [mynewt-nimble] andrzej-kaczmarek opened a new pull request #1045: nimble/ll: Simplify phy switching in scanner

[GitBox <gi...@apache.org>]

andrzej-kaczmarek opened a new pull request #1045:
URL: https://github.com/apache/mynewt-nimble/pull/1045


   This aims to make phy switching in scanner really simple.
   
   Currently we have two separate scan windows (one for each phy) that
   usually move at different interval and we are trying to select best
   window to scan at the given moment. To make things simpler we can use
   a common interval for both phys and scan them back to back. This means
   we effectively have single scan window with phy switch at some point
   during the window.
   
   This is possible because we can select any window/interval values and
   do not need to strictly follow those requested by host. Obviously we'll
   try to select parameters that are somehow related to requested ones, so
   we do as follows:
   - use duty cycle for each phy as a guideline to calculate sub-window
     duration for each phy
   - use larger interval of both phys as interval
   - scale phy window duration up or down to have proper duty cycle at
     selected interval
   
   So basically if host requests the same interval for both phys, we will
   use sub-window duration for each phy as requested, unless both do not
   fit in single interval (i.e. sum of window duration for each phy is
   larger than interval) so we'll scale them down in such case to fit.
   If intervals on both phys are not the same, we'll recalculate windows
   to have the same duty cycle as requested, but with different (common)
   interval.
   
   The same calculations also work well for single phy since in that case
   one of phys will have window=0 which means also its duty cycle will be
   calculated as 0.


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[GitHub] [mynewt-nimble] sjanc commented on a change in pull request #1045: nimble/ll: Simplify phy switching in scanner

[GitBox <gi...@apache.org>]

sjanc commented on a change in pull request #1045:
URL: https://github.com/apache/mynewt-nimble/pull/1045#discussion_r722148485



##########
File path: nimble/controller/src/ble_ll_scan.c
##########
@@ -2570,17 +2533,70 @@ ble_ll_scan_hci_set_params(const uint8_t *cmdbuf, uint8_t len)
     scanp = &g_ble_ll_scan_params.scan_phys[PHY_UNCODED];
     scanp->configured = 1;
     scanp->scan_type = cmd->scan_type;
-    scanp->timing.interval = ble_ll_scan_time_hci_to_ticks(scan_itvl);
-    scanp->timing.window = ble_ll_scan_time_hci_to_ticks(scan_window);
 
 #if (BLE_LL_SCAN_PHY_NUMBER == 2)
     scanp = &g_ble_ll_scan_params.scan_phys[PHY_CODED];
     scanp->configured = 0;
 #endif
 
+    scan_win = &g_ble_ll_scan_params.scan_win;
+    scan_win->tick_start = 0;
+    scan_win->tick_switch_phy = ble_ll_scan_time_hci_to_ticks(scan_window);
+    scan_win->tick_end = scan_win->tick_switch_phy;
+    scan_win->tick_next_win = ble_ll_scan_time_hci_to_ticks(scan_itvl);
+
     return 0;
 }
 
+static inline uint32_t

Review comment:
       nitpick: not a huge fan of static inline in c files :-)




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