spi: stm32: make spurious and overrun interrupts visible

We do not expect to receive spurious interrupts so rise a warning
if it happens.

RX overrun is an error condition that signals a corrupted RX
stream both in dma and in irq modes. Report the error and
abort the transfer in either cases.
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Link: https://lore.kernel.org/r/1612551572-495-9-git-send-email-alain.volmat@foss.st.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-stm32.c

@@ -895,8 +895,8 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 		mask |= STM32H7_SPI_SR_RXP;
 
 	if (!(sr & mask)) {
-		dev_dbg(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
-			sr, ier);
+		dev_warn(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
+			 sr, ier);
 		spin_unlock_irqrestore(&spi->lock, flags);
 		return IRQ_NONE;
 	}
@@ -923,15 +923,8 @@ static irqreturn_t stm32h7_spi_irq_thread(int irq, void *dev_id)
 	}
 
 	if (sr & STM32H7_SPI_SR_OVR) {
-		dev_warn(spi->dev, "Overrun: received value discarded\n");
-		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
-			stm32h7_spi_read_rxfifo(spi, false);
-		/*
-		 * If overrun is detected while using DMA, it means that
-		 * something went wrong, so stop the current transfer
-		 */
-		if (spi->cur_usedma)
-			end = true;
+		dev_err(spi->dev, "Overrun: RX data lost\n");
+		end = true;
 	}
 
 	if (sr & STM32H7_SPI_SR_EOT) {