diff --git a/drivers/spi/spi-dw-mid.c b/drivers/spi/spi-dw-mid.c index 846e3db91329..abd6955ad1f7 100644 --- a/drivers/spi/spi-dw-mid.c +++ b/drivers/spi/spi-dw-mid.c @@ -248,6 +248,49 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_tx(struct dw_spi *dws, return txdesc; } +static inline bool dw_spi_dma_rx_busy(struct dw_spi *dws) +{ + return !!(dw_readl(dws, DW_SPI_SR) & SR_RF_NOT_EMPT); +} + +static int dw_spi_dma_wait_rx_done(struct dw_spi *dws) +{ + int retry = WAIT_RETRIES; + struct spi_delay delay; + unsigned long ns, us; + u32 nents; + + /* + * It's unlikely that DMA engine is still doing the data fetching, but + * if it's let's give it some reasonable time. The timeout calculation + * is based on the synchronous APB/SSI reference clock rate, on a + * number of data entries left in the Rx FIFO, times a number of clock + * periods normally needed for a single APB read/write transaction + * without PREADY signal utilized (which is true for the DW APB SSI + * controller). + */ + nents = dw_readl(dws, DW_SPI_RXFLR); + ns = 4U * NSEC_PER_SEC / dws->max_freq * nents; + if (ns <= NSEC_PER_USEC) { + delay.unit = SPI_DELAY_UNIT_NSECS; + delay.value = ns; + } else { + us = DIV_ROUND_UP(ns, NSEC_PER_USEC); + delay.unit = SPI_DELAY_UNIT_USECS; + delay.value = clamp_val(us, 0, USHRT_MAX); + } + + while (dw_spi_dma_rx_busy(dws) && retry--) + spi_delay_exec(&delay, NULL); + + if (retry < 0) { + dev_err(&dws->master->dev, "Rx hanged up\n"); + return -EIO; + } + + return 0; +} + /* * dws->dma_chan_busy is set before the dma transfer starts, callback for rx * channel will clear a corresponding bit. @@ -358,7 +401,10 @@ static int mid_spi_dma_transfer(struct dw_spi *dws, struct spi_transfer *xfer) return ret; } - return 0; + if (rxdesc && dws->master->cur_msg->status == -EINPROGRESS) + ret = dw_spi_dma_wait_rx_done(dws); + + return ret; } static void mid_spi_dma_stop(struct dw_spi *dws)