mpfs_corespi: fix semaphore race condition

SPI TX_DONE interrupt can be received after a semaphore timeout, but before interrupts are disabled. This will leave the semaphore to the signaled state. After a timeout the semaphore is always reset to non-signaled state to fix this race condition. Signed-off-by: Tero Salminen <[email protected]>
tiiuae · Apr 2, 2024 · 5e30e33 · 5e30e33
1 parent b037ee8
commit 5e30e33
Showing 1 changed file with 12 additions and 0 deletions.
diff --git a/arch/risc-v/src/mpfs/mpfs_corespi.c b/arch/risc-v/src/mpfs/mpfs_corespi.c
@@ -928,6 +928,18 @@ static void mpfs_spi_irq_exchange(struct mpfs_spi_priv_s *priv,
                                 MPFS_SPI_INTTXDONE,
                                 0);
 
+  /* TX_DONE interrupt can be received after a semaphore timeout, but before
+   * interrupts are disabled. This will leave the semaphore to the signaled
+   * state.
+   * After a timeout the semaphore is always reset to non-signaled state
+   * to fix this race condition.
+   */
+
+  if (priv->error == -ETIMEDOUT)
+    {
+      nxsem_reset(&priv->sem_isr, 0);
+    }
+
   putreg32(MPFS_SPI_TXCHUNDRUN |
            MPFS_SPI_RXCHOVRFLW |
            MPFS_SPI_DATA_RX |