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@@ -217,6 +217,44 @@ struct spi_bus_lock_dev_t {
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uint32_t mask; ///< Bitwise OR-ed mask of the REQ, PEND, LOCK bits of this device
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};
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+/**
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+ * @note 1
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+ * This critical section is only used to fix such condition:
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+ *
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+ * define: lock_bits = (lock->status & LOCK_MASK) >> LOCK_SHIFT; This `lock_bits` is the Bit 29-20 of the lock->status
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+ *
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+ * 1. spi_hdl_1:
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+ * acquire_end_core():
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+ * uint32_t status = lock_status_clear(lock, dev_handle->mask & LOCK_MASK);
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+ *
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+ * Becuase this is the first `spi_hdl_1`, so after this , lock_bits == 0`b0. status == 0
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+ *
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+ * 2. spi_hdl_2:
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+ * acquire_core:
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+ * uint32_t status = lock_status_fetch_set(lock, dev_handle->mask & LOCK_MASK);
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+ *
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+ * Then here status is 0`b0, but lock_bits == 0`b10. Because this is the `spi_hdl_2`
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+ *
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+ * 3. spi_hdl_2:
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+ * `acquire_core` return true, because status == 0. `spi_bus_lock_acquire_start(spi_hdl_2)` then won't block.
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+ *
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+ * 4. spi_hdl_2:
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+ * spi_device_polling_end(spi_hdl_2).
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+ *
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+ * 5. spi_hdl_1:
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+ * acquire_end_core:
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+ * status is 0, so it cleas the lock->acquiring_dev
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+ *
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+ * 6. spi_hdl_2:
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+ * spi_device_polling_end:
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+ * assert(handle == get_acquiring_dev(host)); Fail
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+ *
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+ * @note 2
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+ * Only use this critical section in this condition. The critical section scope is limited to the smallest.
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+ * As `spi_bus_lock` influences the all the SPIs (including MSPI) a lot!
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+ */
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+portMUX_TYPE s_spinlock = portMUX_INITIALIZER_UNLOCKED;
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+
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DRAM_ATTR static const char TAG[] = "bus_lock";
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#define LOCK_CHECK(a, str, ret_val, ...) \
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@@ -323,7 +361,11 @@ SPI_MASTER_ATTR static inline void req_core(spi_bus_lock_dev_t *dev_handle)
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SPI_MASTER_ISR_ATTR static inline bool acquire_core(spi_bus_lock_dev_t *dev_handle)
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{
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spi_bus_lock_t* lock = dev_handle->parent;
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+
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+ //For this critical section, search `@note 1` in this file, to know details
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+ portENTER_CRITICAL_SAFE(&s_spinlock);
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uint32_t status = lock_status_fetch_set(lock, dev_handle->mask & LOCK_MASK);
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+ portEXIT_CRITICAL_SAFE(&s_spinlock);
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// Check all bits except WEAK_BG
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if ((status & (BG_MASK | LOCK_MASK)) == 0) {
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@@ -401,10 +443,14 @@ schedule_core(spi_bus_lock_t *lock, uint32_t status, spi_bus_lock_dev_t **out_de
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IRAM_ATTR static inline void acquire_end_core(spi_bus_lock_dev_t *dev_handle)
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{
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spi_bus_lock_t* lock = dev_handle->parent;
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- uint32_t status = lock_status_clear(lock, dev_handle->mask & LOCK_MASK);
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spi_bus_lock_dev_t* desired_dev = NULL;
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+ //For this critical section, search `@note 1` in this file, to know details
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+ portENTER_CRITICAL_SAFE(&s_spinlock);
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+ uint32_t status = lock_status_clear(lock, dev_handle->mask & LOCK_MASK);
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bool invoke_bg = !schedule_core(lock, status, &desired_dev);
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+ portEXIT_CRITICAL_SAFE(&s_spinlock);
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+
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if (invoke_bg) {
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bg_enable(lock);
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} else if (desired_dev) {
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