fix[STM32][SPI]: keep async route decision stable per message

snapshot scheduler and interrupt state once per SPI message
reuse the message-level async route decision for all split chunks
disable DMA and interrupt paths consistently when async transfer is unavailable
avoid mixed async and polling policies within one logical SPI transfer

Author: wdfk-prog

bsp/stm32/libraries/HAL_Drivers/drivers/drv_spi.c

@@ -416,6 +416,24 @@ static rt_ssize_t spixfer(struct rt_spi_device *device, struct rt_spi_message *m
     rt_tick_t timeout_tick = rt_tick_from_millisecond(timeout_ms);
 #endif /* BSP_SPI_USING_IRQ */
 
+#if defined(BSP_SPI_USING_DMA) || defined(BSP_SPI_USING_INT)
+    /*
+     * Snapshot the call context once for the whole SPI message.
+     *
+     * The async route decision must stay stable across all chunks split from
+     * one message. Re-evaluating scheduler/IRQ state per chunk could route
+     * one logical SPI transfer through different async/polling policies.
+     *
+     * A thread switch or interrupt can happen while waiting for async transfer
+     * completion, but execution still resumes in the same spixfer() call
+     * context. Therefore, the route policy should follow this message-level
+     * context instead of re-sampling a transient runtime state.
+     */
+    const rt_bool_t scheduler_available = rt_scheduler_is_available();
+    const rt_bool_t irq_disabled = rt_hw_interrupt_is_disabled();
+    const rt_bool_t async_allowed = (scheduler_available && !irq_disabled);
+#endif /* defined(BSP_SPI_USING_DMA) || defined(BSP_SPI_USING_INT) */
+
     if (message->cs_take && !(device->config.mode & RT_SPI_NO_CS) && (device->cs_pin != PIN_NONE))
     {
         if (device->config.mode & RT_SPI_CS_HIGH)
@@ -462,8 +480,7 @@ static rt_ssize_t spixfer(struct rt_spi_device *device, struct rt_spi_message *m
         {
             recv_buf = (rt_uint8_t *)message->recv_buf + already_send_length;
         }
-        const rt_bool_t scheduler_available = rt_scheduler_is_available();
-        const rt_bool_t irq_disabled = rt_hw_interrupt_is_disabled();
+
 #ifdef BSP_SPI_USING_DMA
         const rt_uint8_t *dma_send_buf = send_buf;
         rt_uint8_t *dma_recv_buf = recv_buf;
@@ -483,7 +500,7 @@ static rt_ssize_t spixfer(struct rt_spi_device *device, struct rt_spi_message *m
         rt_bool_t use_rx_dma = RT_FALSE;
 #endif /* BSP_SPI_RX_USING_DMA */
 
-        if (!scheduler_available || irq_disabled)
+        if (!async_allowed)
         {
             use_rx_dma = use_tx_dma = dma_eligible = RT_FALSE;
         }
@@ -541,7 +558,7 @@ static rt_ssize_t spixfer(struct rt_spi_device *device, struct rt_spi_message *m
 #else
         rt_bool_t use_rx_int = RT_FALSE;
 #endif /* BSP_SPI_RX_USING_INT */
-        if (!scheduler_available || irq_disabled)
+        if (!async_allowed)
         {
             use_rx_int = use_tx_int = int_eligible = RT_FALSE;
         }