| Message ID | 1425219333-3014-1-git-send-email-anton_bondarenko@mentor.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
Hi Anton, Thanks for your patch, please see my comments below, and I'm also little for performance if we using interrupt for the last tail data in rxfifo, how about just read out the data from rxfifo directly? On Sun, Mar 01, 2015 at 03:15:31PM +0100, Anton Bondarenko wrote: > RX DMA tail data handling doesn't work correctly in many cases with current > implementation. It happens because SPI core was setup to generates both > RX watermark level and RX DATA TAIL events incorrectly. SPI transfer triggering > for DMA also done in wrong way. > > SPI client wants to transfer 70 words for example. The old DMA implementation > setup RX DATA TAIL equal 6 words. In this case RX DMA event will be generated > after 6 words read from RX FIFO. In this case the garbage can be read out from > RX FIFO because SPI HW does not receive all required words to trigger > RX watermark event. > > New implementation change handling of RX data tail. DMA is used to process all > TX data and only full chunks of RX data with size aligned to FIFO/2. > Driver is waiting until both TX and RX DMA transaction done and all TX data are pushed out. > At that moment there is only RX data tail in the RX FIFO. This data read out using PIO. > > Transfer triggering changed to avoid RX data loss. > > Signed-off-by: Anton Bondarenko <anton_bondarenko@mentor.com> > --- > drivers/spi/spi-imx.c | 100 +++++++++++++++++++++++++++++++------------------- > 1 file changed, 62 insertions(+), 38 deletions(-) > > diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c > index 6fea4af..9df96c8 100644 > --- a/drivers/spi/spi-imx.c > +++ b/drivers/spi/spi-imx.c > @@ -53,6 +53,7 @@ > /* generic defines to abstract from the different register layouts */ > #define MXC_INT_RR (1 << 0) /* Receive data ready interrupt */ > #define MXC_INT_TE (1 << 1) /* Transmit FIFO empty interrupt */ > +#define MXC_INT_TCEN BIT(7) /* Transfer complete */ > > /* The maximum bytes that a sdma BD can transfer.*/ > #define MAX_SDMA_BD_BYTES (1 << 15) > @@ -104,9 +105,7 @@ struct spi_imx_data { > unsigned int dma_is_inited; > unsigned int dma_finished; > bool usedma; > - u32 rx_wml; > - u32 tx_wml; > - u32 rxt_wml; > + u32 wml; > struct completion dma_rx_completion; > struct completion dma_tx_completion; > > @@ -201,8 +200,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi, > { > struct spi_imx_data *spi_imx = spi_master_get_devdata(master); > > - if (spi_imx->dma_is_inited && (transfer->len > spi_imx->rx_wml) > - && (transfer->len > spi_imx->tx_wml)) > + if (spi_imx->dma_is_inited && (transfer->len > spi_imx->wml)) > return true; > return false; > } > @@ -227,6 +225,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi, > #define MX51_ECSPI_INT 0x10 > #define MX51_ECSPI_INT_TEEN (1 << 0) > #define MX51_ECSPI_INT_RREN (1 << 3) > +#define MX51_ECSPI_INT_TCEN BIT(7) > > #define MX51_ECSPI_DMA 0x14 > #define MX51_ECSPI_DMA_TX_WML_OFFSET 0 > @@ -291,6 +290,9 @@ static void __maybe_unused mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int > if (enable & MXC_INT_RR) > val |= MX51_ECSPI_INT_RREN; > > + if (enable & MXC_INT_TCEN) > + val |= MX51_ECSPI_INT_TCEN; > + > writel(val, spi_imx->base + MX51_ECSPI_INT); > } > > @@ -310,8 +312,9 @@ static void __maybe_unused mx51_ecspi_trigger(struct spi_imx_data *spi_imx) > static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, > struct spi_imx_config *config) > { > - u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0; > - u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg; > + u32 ctrl = MX51_ECSPI_CTRL_ENABLE, dma = 0; > + u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG); > + > u32 clk = config->speed_hz, delay; > > /* > @@ -368,21 +371,9 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, > * and enable DMA request. > */ > if (spi_imx->dma_is_inited) { > - dma = readl(spi_imx->base + MX51_ECSPI_DMA); > - > - spi_imx->tx_wml = spi_imx_get_fifosize(spi_imx) / 2; > - spi_imx->rx_wml = spi_imx_get_fifosize(spi_imx) / 2; > - spi_imx->rxt_wml = spi_imx_get_fifosize(spi_imx) / 2; > - rx_wml_cfg = spi_imx->rx_wml << MX51_ECSPI_DMA_RX_WML_OFFSET; > - tx_wml_cfg = spi_imx->tx_wml << MX51_ECSPI_DMA_TX_WML_OFFSET; > - rxt_wml_cfg = spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET; > - dma = (dma & ~MX51_ECSPI_DMA_TX_WML_MASK > - & ~MX51_ECSPI_DMA_RX_WML_MASK > - & ~MX51_ECSPI_DMA_RXT_WML_MASK) > - | rx_wml_cfg | tx_wml_cfg | rxt_wml_cfg > - |(1 << MX51_ECSPI_DMA_TEDEN_OFFSET) > - |(1 << MX51_ECSPI_DMA_RXDEN_OFFSET) > - |(1 << MX51_ECSPI_DMA_RXTDEN_OFFSET); > + dma = (spi_imx->wml - 1) << MX51_ECSPI_DMA_RX_WML_OFFSET > + | (1 << MX51_ECSPI_DMA_TEDEN_OFFSET) > + | (1 << MX51_ECSPI_DMA_RXDEN_OFFSET); > why set tx_wml to 0? Big performance will be impacted. Or there is known issue here? > writel(dma, spi_imx->base + MX51_ECSPI_DMA); > } > @@ -826,6 +817,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, > if (of_machine_is_compatible("fsl,imx6dl")) > return 0; > > + spi_imx->wml = spi_imx_get_fifosize(spi_imx) / 2; > + > /* Prepare for TX DMA: */ > master->dma_tx = dma_request_slave_channel(dev, "tx"); > if (!master->dma_tx) { > @@ -837,7 +830,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, > slave_config.direction = DMA_MEM_TO_DEV; > slave_config.dst_addr = res->start + MXC_CSPITXDATA; > slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > - slave_config.dst_maxburst = spi_imx_get_fifosize(spi_imx) / 2; > + slave_config.dst_maxburst = spi_imx_get_fifosize(spi_imx) > + - spi_imx->wml; > ret = dmaengine_slave_config(master->dma_tx, &slave_config); > if (ret) { > dev_err(dev, "error in TX dma configuration.\n"); > @@ -855,7 +849,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, > slave_config.direction = DMA_DEV_TO_MEM; > slave_config.src_addr = res->start + MXC_CSPIRXDATA; > slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > - slave_config.src_maxburst = spi_imx_get_fifosize(spi_imx) / 2; > + slave_config.src_maxburst = spi_imx_get_fifosize(spi_imx) > + - spi_imx->wml; > ret = dmaengine_slave_config(master->dma_rx, &slave_config); > if (ret) { > dev_err(dev, "error in RX dma configuration.\n"); > @@ -896,8 +891,7 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, > struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL; > int ret; > unsigned long timeout; > - u32 dma; > - int left; > + const int left = transfer->len % spi_imx->wml; > struct spi_master *master = spi_imx->bitbang.master; > struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg; > > @@ -914,9 +908,23 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, > } > > if (rx) { > + /* Cut RX data tail */ > + const unsigned int old_nents = rx->nents; > + > + WARN_ON(sg_dma_len(&rx->sgl[rx->nents - 1]) < left); > + sg_dma_len(&rx->sgl[rx->nents - 1]) -= left; > + if (sg_dma_len(&rx->sgl[rx->nents - 1]) == 0) > + --rx->nents; > + > desc_rx = dmaengine_prep_slave_sg(master->dma_rx, > rx->sgl, rx->nents, DMA_FROM_DEVICE, > DMA_PREP_INTERRUPT | DMA_CTRL_ACK); > + > + /* Restore old SG table state */ > + if (old_nents > rx->nents) > + ++rx->nents; > + sg_dma_len(&rx->sgl[rx->nents - 1]) += left; > + > if (!desc_rx) > goto no_dma; > > @@ -931,17 +939,10 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, > /* Trigger the cspi module. */ > spi_imx->dma_finished = 0; > > - dma = readl(spi_imx->base + MX51_ECSPI_DMA); > - dma = dma & (~MX51_ECSPI_DMA_RXT_WML_MASK); > - /* Change RX_DMA_LENGTH trigger dma fetch tail data */ > - left = transfer->len % spi_imx->rxt_wml; > - if (left) > - writel(dma | (left << MX51_ECSPI_DMA_RXT_WML_OFFSET), > - spi_imx->base + MX51_ECSPI_DMA); > + dma_async_issue_pending(master->dma_rx); > + dma_async_issue_pending(master->dma_tx); It's better keep the same sequence as before, issue_pending after trigger. > spi_imx->devtype_data->trigger(spi_imx); > > - dma_async_issue_pending(master->dma_tx); > - dma_async_issue_pending(master->dma_rx); > /* Wait SDMA to finish the data transfer.*/ > timeout = wait_for_completion_timeout(&spi_imx->dma_tx_completion, > IMX_DMA_TIMEOUT); > @@ -950,6 +951,7 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, > dev_driver_string(&master->dev), > dev_name(&master->dev)); > dmaengine_terminate_all(master->dma_tx); > + dmaengine_terminate_all(master->dma_rx); > } else { > timeout = wait_for_completion_timeout( > &spi_imx->dma_rx_completion, IMX_DMA_TIMEOUT); > @@ -959,10 +961,28 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, > dev_name(&master->dev)); > spi_imx->devtype_data->reset(spi_imx); > dmaengine_terminate_all(master->dma_rx); > + } else if (left) { > + dma_sync_sg_for_cpu(master->dma_rx->device->dev, > + rx->sgl, rx->nents, > + DMA_FROM_DEVICE); How about only for the last entry? > + > + spi_imx->rx_buf = transfer->rx_buf > + + (transfer->len - left); > + spi_imx->txfifo = left; > + reinit_completion(&spi_imx->xfer_done); > + > + spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TCEN); > + > + timeout = wait_for_completion_timeout( > + &spi_imx->xfer_done, IMX_DMA_TIMEOUT); > + if (!timeout) { > + pr_warn("%s %s: I/O Error in RX tail\n", > + dev_driver_string(&master->dev), > + dev_name(&master->dev)); > + } > } > - writel(dma | > - spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET, > - spi_imx->base + MX51_ECSPI_DMA); > + > + writel(0, spi_imx->base + MX51_ECSPI_DMA); That may cause the next DMA transfer failed without setup_transfer calling, because you clear the setting in mx51_ecspi_config for DMA. Please remove writel(0, spi_imx->base + MX51_ECSPI_DMA); > } > > spi_imx->dma_finished = 1; > @@ -1009,6 +1029,10 @@ static int spi_imx_transfer(struct spi_device *spi, > int ret; > struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master); > > + /* flush rxfifo before transfer */ > + while (spi_imx->devtype_data->rx_available(spi_imx)) > + spi_imx->rx(spi_imx); > + Why flush rxfifo here? > if (spi_imx->bitbang.master->can_dma && > spi_imx_can_dma(spi_imx->bitbang.master, spi, transfer)) { > spi_imx->usedma = true; > -- > 2.3.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index 6fea4af..9df96c8 100644 --- a/drivers/spi/spi-imx.c +++ b/drivers/spi/spi-imx.c @@ -53,6 +53,7 @@ /* generic defines to abstract from the different register layouts */ #define MXC_INT_RR (1 << 0) /* Receive data ready interrupt */ #define MXC_INT_TE (1 << 1) /* Transmit FIFO empty interrupt */ +#define MXC_INT_TCEN BIT(7) /* Transfer complete */ /* The maximum bytes that a sdma BD can transfer.*/ #define MAX_SDMA_BD_BYTES (1 << 15) @@ -104,9 +105,7 @@ struct spi_imx_data { unsigned int dma_is_inited; unsigned int dma_finished; bool usedma; - u32 rx_wml; - u32 tx_wml; - u32 rxt_wml; + u32 wml; struct completion dma_rx_completion; struct completion dma_tx_completion; @@ -201,8 +200,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi, { struct spi_imx_data *spi_imx = spi_master_get_devdata(master); - if (spi_imx->dma_is_inited && (transfer->len > spi_imx->rx_wml) - && (transfer->len > spi_imx->tx_wml)) + if (spi_imx->dma_is_inited && (transfer->len > spi_imx->wml)) return true; return false; } @@ -227,6 +225,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi, #define MX51_ECSPI_INT 0x10 #define MX51_ECSPI_INT_TEEN (1 << 0) #define MX51_ECSPI_INT_RREN (1 << 3) +#define MX51_ECSPI_INT_TCEN BIT(7) #define MX51_ECSPI_DMA 0x14 #define MX51_ECSPI_DMA_TX_WML_OFFSET 0 @@ -291,6 +290,9 @@ static void __maybe_unused mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int if (enable & MXC_INT_RR) val |= MX51_ECSPI_INT_RREN; + if (enable & MXC_INT_TCEN) + val |= MX51_ECSPI_INT_TCEN; + writel(val, spi_imx->base + MX51_ECSPI_INT); } @@ -310,8 +312,9 @@ static void __maybe_unused mx51_ecspi_trigger(struct spi_imx_data *spi_imx) static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, struct spi_imx_config *config) { - u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0; - u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg; + u32 ctrl = MX51_ECSPI_CTRL_ENABLE, dma = 0; + u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG); + u32 clk = config->speed_hz, delay; /* @@ -368,21 +371,9 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx, * and enable DMA request. */ if (spi_imx->dma_is_inited) { - dma = readl(spi_imx->base + MX51_ECSPI_DMA); - - spi_imx->tx_wml = spi_imx_get_fifosize(spi_imx) / 2; - spi_imx->rx_wml = spi_imx_get_fifosize(spi_imx) / 2; - spi_imx->rxt_wml = spi_imx_get_fifosize(spi_imx) / 2; - rx_wml_cfg = spi_imx->rx_wml << MX51_ECSPI_DMA_RX_WML_OFFSET; - tx_wml_cfg = spi_imx->tx_wml << MX51_ECSPI_DMA_TX_WML_OFFSET; - rxt_wml_cfg = spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET; - dma = (dma & ~MX51_ECSPI_DMA_TX_WML_MASK - & ~MX51_ECSPI_DMA_RX_WML_MASK - & ~MX51_ECSPI_DMA_RXT_WML_MASK) - | rx_wml_cfg | tx_wml_cfg | rxt_wml_cfg - |(1 << MX51_ECSPI_DMA_TEDEN_OFFSET) - |(1 << MX51_ECSPI_DMA_RXDEN_OFFSET) - |(1 << MX51_ECSPI_DMA_RXTDEN_OFFSET); + dma = (spi_imx->wml - 1) << MX51_ECSPI_DMA_RX_WML_OFFSET + | (1 << MX51_ECSPI_DMA_TEDEN_OFFSET) + | (1 << MX51_ECSPI_DMA_RXDEN_OFFSET); writel(dma, spi_imx->base + MX51_ECSPI_DMA); } @@ -826,6 +817,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, if (of_machine_is_compatible("fsl,imx6dl")) return 0; + spi_imx->wml = spi_imx_get_fifosize(spi_imx) / 2; + /* Prepare for TX DMA: */ master->dma_tx = dma_request_slave_channel(dev, "tx"); if (!master->dma_tx) { @@ -837,7 +830,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, slave_config.direction = DMA_MEM_TO_DEV; slave_config.dst_addr = res->start + MXC_CSPITXDATA; slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; - slave_config.dst_maxburst = spi_imx_get_fifosize(spi_imx) / 2; + slave_config.dst_maxburst = spi_imx_get_fifosize(spi_imx) + - spi_imx->wml; ret = dmaengine_slave_config(master->dma_tx, &slave_config); if (ret) { dev_err(dev, "error in TX dma configuration.\n"); @@ -855,7 +849,8 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx, slave_config.direction = DMA_DEV_TO_MEM; slave_config.src_addr = res->start + MXC_CSPIRXDATA; slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; - slave_config.src_maxburst = spi_imx_get_fifosize(spi_imx) / 2; + slave_config.src_maxburst = spi_imx_get_fifosize(spi_imx) + - spi_imx->wml; ret = dmaengine_slave_config(master->dma_rx, &slave_config); if (ret) { dev_err(dev, "error in RX dma configuration.\n"); @@ -896,8 +891,7 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL; int ret; unsigned long timeout; - u32 dma; - int left; + const int left = transfer->len % spi_imx->wml; struct spi_master *master = spi_imx->bitbang.master; struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg; @@ -914,9 +908,23 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, } if (rx) { + /* Cut RX data tail */ + const unsigned int old_nents = rx->nents; + + WARN_ON(sg_dma_len(&rx->sgl[rx->nents - 1]) < left); + sg_dma_len(&rx->sgl[rx->nents - 1]) -= left; + if (sg_dma_len(&rx->sgl[rx->nents - 1]) == 0) + --rx->nents; + desc_rx = dmaengine_prep_slave_sg(master->dma_rx, rx->sgl, rx->nents, DMA_FROM_DEVICE, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + + /* Restore old SG table state */ + if (old_nents > rx->nents) + ++rx->nents; + sg_dma_len(&rx->sgl[rx->nents - 1]) += left; + if (!desc_rx) goto no_dma; @@ -931,17 +939,10 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, /* Trigger the cspi module. */ spi_imx->dma_finished = 0; - dma = readl(spi_imx->base + MX51_ECSPI_DMA); - dma = dma & (~MX51_ECSPI_DMA_RXT_WML_MASK); - /* Change RX_DMA_LENGTH trigger dma fetch tail data */ - left = transfer->len % spi_imx->rxt_wml; - if (left) - writel(dma | (left << MX51_ECSPI_DMA_RXT_WML_OFFSET), - spi_imx->base + MX51_ECSPI_DMA); + dma_async_issue_pending(master->dma_rx); + dma_async_issue_pending(master->dma_tx); spi_imx->devtype_data->trigger(spi_imx); - dma_async_issue_pending(master->dma_tx); - dma_async_issue_pending(master->dma_rx); /* Wait SDMA to finish the data transfer.*/ timeout = wait_for_completion_timeout(&spi_imx->dma_tx_completion, IMX_DMA_TIMEOUT); @@ -950,6 +951,7 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, dev_driver_string(&master->dev), dev_name(&master->dev)); dmaengine_terminate_all(master->dma_tx); + dmaengine_terminate_all(master->dma_rx); } else { timeout = wait_for_completion_timeout( &spi_imx->dma_rx_completion, IMX_DMA_TIMEOUT); @@ -959,10 +961,28 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx, dev_name(&master->dev)); spi_imx->devtype_data->reset(spi_imx); dmaengine_terminate_all(master->dma_rx); + } else if (left) { + dma_sync_sg_for_cpu(master->dma_rx->device->dev, + rx->sgl, rx->nents, + DMA_FROM_DEVICE); + + spi_imx->rx_buf = transfer->rx_buf + + (transfer->len - left); + spi_imx->txfifo = left; + reinit_completion(&spi_imx->xfer_done); + + spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TCEN); + + timeout = wait_for_completion_timeout( + &spi_imx->xfer_done, IMX_DMA_TIMEOUT); + if (!timeout) { + pr_warn("%s %s: I/O Error in RX tail\n", + dev_driver_string(&master->dev), + dev_name(&master->dev)); + } } - writel(dma | - spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET, - spi_imx->base + MX51_ECSPI_DMA); + + writel(0, spi_imx->base + MX51_ECSPI_DMA); } spi_imx->dma_finished = 1; @@ -1009,6 +1029,10 @@ static int spi_imx_transfer(struct spi_device *spi, int ret; struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master); + /* flush rxfifo before transfer */ + while (spi_imx->devtype_data->rx_available(spi_imx)) + spi_imx->rx(spi_imx); + if (spi_imx->bitbang.master->can_dma && spi_imx_can_dma(spi_imx->bitbang.master, spi, transfer)) { spi_imx->usedma = true;
RX DMA tail data handling doesn't work correctly in many cases with current implementation. It happens because SPI core was setup to generates both RX watermark level and RX DATA TAIL events incorrectly. SPI transfer triggering for DMA also done in wrong way. SPI client wants to transfer 70 words for example. The old DMA implementation setup RX DATA TAIL equal 6 words. In this case RX DMA event will be generated after 6 words read from RX FIFO. In this case the garbage can be read out from RX FIFO because SPI HW does not receive all required words to trigger RX watermark event. New implementation change handling of RX data tail. DMA is used to process all TX data and only full chunks of RX data with size aligned to FIFO/2. Driver is waiting until both TX and RX DMA transaction done and all TX data are pushed out. At that moment there is only RX data tail in the RX FIFO. This data read out using PIO. Transfer triggering changed to avoid RX data loss. Signed-off-by: Anton Bondarenko <anton_bondarenko@mentor.com> --- drivers/spi/spi-imx.c | 100 +++++++++++++++++++++++++++++++------------------- 1 file changed, 62 insertions(+), 38 deletions(-)