From 0327f0b881dc5645c7ba670331e822cdaa8c5e09 Mon Sep 17 00:00:00 2001 From: Serge Semin Date: Fri, 15 May 2020 13:47:42 +0300 Subject: [PATCH] spi: dw: Clear DMAC register when done or stopped If DMAC register is left uncleared any further DMAless transfers may cause the DMAC hardware handshaking interface getting activated. So the next DMA-based Rx/Tx transaction will be started right after the dma_async_issue_pending() method is invoked even if no DMATDLR/DMARDLR conditions are met. This at the same time may cause the Tx/Rx FIFO buffers underrun/overrun. In order to fix this we must clear DMAC register after a current DMA-based transaction is finished. Co-developed-by: Georgy Vlasov Signed-off-by: Georgy Vlasov Signed-off-by: Serge Semin Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20200515104758.6934-4-Sergey.Semin@baikalelectronics.ru Signed-off-by: Mark Brown --- drivers/spi/spi-dw-mid.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/spi/spi-dw-mid.c b/drivers/spi/spi-dw-mid.c index 177e1f5ec62b..f9757a370699 100644 --- a/drivers/spi/spi-dw-mid.c +++ b/drivers/spi/spi-dw-mid.c @@ -106,6 +106,8 @@ static void mid_spi_dma_exit(struct dw_spi *dws) dmaengine_terminate_sync(dws->rxchan); dma_release_channel(dws->rxchan); } + + dw_writel(dws, DW_SPI_DMACR, 0); } static irqreturn_t dma_transfer(struct dw_spi *dws) @@ -152,6 +154,8 @@ static void dw_spi_dma_tx_done(void *arg) clear_bit(TX_BUSY, &dws->dma_chan_busy); if (test_bit(RX_BUSY, &dws->dma_chan_busy)) return; + + dw_writel(dws, DW_SPI_DMACR, 0); spi_finalize_current_transfer(dws->master); } @@ -199,6 +203,8 @@ static void dw_spi_dma_rx_done(void *arg) clear_bit(RX_BUSY, &dws->dma_chan_busy); if (test_bit(TX_BUSY, &dws->dma_chan_busy)) return; + + dw_writel(dws, DW_SPI_DMACR, 0); spi_finalize_current_transfer(dws->master); } @@ -292,6 +298,8 @@ static void mid_spi_dma_stop(struct dw_spi *dws) dmaengine_terminate_sync(dws->rxchan); clear_bit(RX_BUSY, &dws->dma_chan_busy); } + + dw_writel(dws, DW_SPI_DMACR, 0); } static const struct dw_spi_dma_ops mfld_dma_ops = { -- 2.11.0