spi: stm32: fix DMA configuration with only one channel

When SPI driver is configured to work only with TX or RX DMA channel
then dmaengine functions can dereferene NULL pointer.

Running full-duplex mode when when only RX or TX DMA channel is
available can cause overrun condition or incorrect writing to transmit
buffer so disable this types of DMA configuration and go back to
interrupt mode.

Signed-off-by: Cezary Gapinski <cezary.gapinski@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 51d7f720127b1fdd6f303b26740ace0cbec9b556..8310f14fe273fe3703d0b8a6a7e51d2d80d1ea7f 100644 (file)
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -427,9 +427,9 @@ static void stm32_spi_disable(struct stm32_spi *spi)
        if (!spi->cur_usedma && spi->rx_buf && (spi->rx_len > 0))
                stm32_spi_read_rxfifo(spi, true);
 
-       if (spi->cur_usedma && spi->tx_buf)
+       if (spi->cur_usedma && spi->dma_tx)
                dmaengine_terminate_all(spi->dma_tx);
-       if (spi->cur_usedma && spi->rx_buf)
+       if (spi->cur_usedma && spi->dma_rx)
                dmaengine_terminate_all(spi->dma_rx);
 
        stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
@@ -750,7 +750,7 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
        spin_lock_irqsave(&spi->lock, flags);
 
        rx_dma_desc = NULL;
-       if (spi->rx_buf) {
+       if (spi->rx_buf && spi->dma_rx) {
                stm32_spi_dma_config(spi, &rx_dma_conf, DMA_DEV_TO_MEM);
                dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
 
@@ -765,7 +765,7 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
        }
 
        tx_dma_desc = NULL;
-       if (spi->tx_buf) {
+       if (spi->tx_buf && spi->dma_tx) {
                stm32_spi_dma_config(spi, &tx_dma_conf, DMA_MEM_TO_DEV);
                dmaengine_slave_config(spi->dma_tx, &tx_dma_conf);
 
@@ -776,8 +776,11 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
                                        DMA_PREP_INTERRUPT);
        }
 
-       if ((spi->tx_buf && !tx_dma_desc) ||
-           (spi->rx_buf && !rx_dma_desc))
+       if ((spi->tx_buf && spi->dma_tx && !tx_dma_desc) ||
+           (spi->rx_buf && spi->dma_rx && !rx_dma_desc))
+               goto dma_desc_error;
+
+       if (spi->cur_comm == SPI_FULL_DUPLEX && (!tx_dma_desc || !rx_dma_desc))
                goto dma_desc_error;
 
        if (rx_dma_desc) {
@@ -822,7 +825,7 @@ static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
        return 1;
 
 dma_submit_error:
-       if (spi->rx_buf)
+       if (spi->dma_rx)
                dmaengine_terminate_all(spi->dma_rx);
 
 dma_desc_error:
@@ -832,6 +835,7 @@ dma_desc_error:
 
        dev_info(spi->dev, "DMA issue: fall back to irq transfer\n");
 
+       spi->cur_usedma = false;
        return stm32_spi_transfer_one_irq(spi);
 }
 
@@ -984,7 +988,7 @@ static int stm32_spi_transfer_one(struct spi_master *master,
        spi->rx_len = spi->rx_buf ? transfer->len : 0;
 
        spi->cur_usedma = (master->can_dma &&
-                          stm32_spi_can_dma(master, spi_dev, transfer));
+                          master->can_dma(master, spi_dev, transfer));
 
        ret = stm32_spi_transfer_one_setup(spi, spi_dev, transfer);
        if (ret) {