dwc2: wait for ahb idle before core reset

Author: hathach

.idea/debugServers/AT32F423VCT7.xml

@@ -168,8 +168,8 @@ TU_ATTR_ALWAYS_INLINE static inline uint8_t tu_u16_high(uint16_t ui16) { return
 TU_ATTR_ALWAYS_INLINE static inline uint8_t tu_u16_low (uint16_t ui16) { return TU_U16_LOW(ui16); }
 
 //------------- Bits -------------//
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tu_bit_set  (uint32_t value, uint8_t pos) { return value | TU_BIT(pos);                  }
-TU_ATTR_ALWAYS_INLINE static inline uint32_t tu_bit_clear(uint32_t value, uint8_t pos) { return value & (~TU_BIT(pos));               }
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tu_bit_set  (uint32_t value, uint8_t pos) { return value | TU_BIT(pos); }
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tu_bit_clear(uint32_t value, uint8_t pos) { return value & (~TU_BIT(pos)); }
 TU_ATTR_ALWAYS_INLINE static inline bool     tu_bit_test (uint32_t value, uint8_t pos) { return (value & TU_BIT(pos)) ? true : false; }
 
 //------------- Min -------------//

.idea/debugServers/ST_LINK.xml

@@ -45,20 +45,26 @@
 //
 //--------------------------------------------------------------------
 static void reset_core(dwc2_regs_t* dwc2) {
+  // The software must check that bit 31 in this register is set to 1 (AHB Master is Idle) before starting any operation
+  while (!(dwc2->grstctl & GRSTCTL_AHBIDL)) {
+  }
+
   // load gsnpsid (it is not readable after reset is asserted)
-  uint32_t gsnpsid = dwc2->gsnpsid;
+  const uint32_t gsnpsid = dwc2->gsnpsid;
 
   // reset core
   dwc2->grstctl |= GRSTCTL_CSRST;
 
   if ((gsnpsid & DWC2_CORE_REV_MASK) < (DWC2_CORE_REV_4_20a & DWC2_CORE_REV_MASK)) {
-    // prior v4.20a CSRST is self-clearing
+    // prior v4.20a: CSRST is self-clearing and the core clears this bit after all the necessary logic is reset in
+    // the core, which can take several clocks, depending on the current state of the core. Once this bit has been
+    // cleared, the software must wait at least 3 PHY clocks before accessing the PHY domain (synchronization delay).
     while (dwc2->grstctl & GRSTCTL_CSRST) {}
   } else {
-    // From v4.20a CSRST bit is write only, CSRT_DONE (w1c) is introduced for checking.
-    // CSRST must also be explicitly cleared
+    // From v4.20a: CSRST bit is write only. The application must clear this bit after checking the bit 29 of this
+    // register i.e Core Soft Reset Done CSRT_DONE (w1c)
     while (!(dwc2->grstctl & GRSTCTL_CSRST_DONE)) {}
-    dwc2->grstctl =  (dwc2->grstctl & ~GRSTCTL_CSRST) | GRSTCTL_CSRST_DONE;
+    dwc2->grstctl = (dwc2->grstctl & ~GRSTCTL_CSRST) | GRSTCTL_CSRST_DONE;
   }
 
   while (!(dwc2->grstctl & GRSTCTL_AHBIDL)) {} // wait for AHB master IDLE