mbedtls aes dma: Fix bug where DMA would complete when the first output descriptor was done, not the last

components/mbedtls/port/esp32s2/aes.c

@@ -405,7 +405,8 @@ static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input,
 {
     lldesc_t stream_in_desc, stream_out_desc;
     lldesc_t *in_desc_head, *out_desc_head;
-    lldesc_t *block_desc = NULL, *block_in_desc, *block_out_desc;
+    lldesc_t *out_desc_tail = NULL; /* pointer to the final output descriptor */
+    lldesc_t *block_desc = NULL, *block_in_desc = NULL, *block_out_desc = NULL;
     size_t lldesc_num;
     uint8_t stream_in[16] = {};
     unsigned stream_bytes = len % AES_BLOCK_BYTES; // bytes which aren't in a full block
@@ -472,8 +473,10 @@ static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input,
         block_in_desc = block_desc;
         block_out_desc = block_desc + lldesc_num;
 
-        lldesc_setup_link(block_desc, input, block_bytes, 0);
-        lldesc_setup_link(block_desc + lldesc_num, output, block_bytes, 0);
+        lldesc_setup_link(block_in_desc, input, block_bytes, 0);
+        lldesc_setup_link(block_out_desc, output, block_bytes, 0);
+
+        out_desc_tail = &block_out_desc[lldesc_num - 1];
     }
 
     /* Any leftover bytes which are appended as an additional DMA list */
@@ -488,6 +491,8 @@ static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input,
             block_in_desc[lldesc_num - 1].empty = (uint32_t)&stream_in_desc;
             block_out_desc[lldesc_num - 1].empty = (uint32_t)&stream_out_desc;
         }
+
+        out_desc_tail = &stream_out_desc;
     }
 
     // block buffers are sent to DMA first, unless there aren't any
@@ -516,7 +521,7 @@ static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input,
 
     /* Start AES operation */
     REG_WRITE(AES_TRIGGER_REG, 1);
-    esp_aes_dma_wait_complete(use_intr, out_desc_head);
+    esp_aes_dma_wait_complete(use_intr, out_desc_tail);