I worried that the delay of the sdma_run_channel0() maybe too long for interrupt context, so I added the workqueues for RX/TX DMA. But tested with bluetooth device, I find that the delay of sdma_run_channel0() is about 8us (tested in imx6dl sabreauto board). I think the delay is acceptable. This patch removes the RX/TX workqueues for DMA, it makes the code more clear. Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx> --- this patch depends on the patch set: http://marc.info/?l=linux-arm-kernel&m=138148839513375&w=2 --- drivers/tty/serial/imx.c | 54 ++++++++------------------------------------- 1 files changed, 10 insertions(+), 44 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 13c2c2d..bb84f8d 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -223,8 +223,7 @@ struct imx_port { struct dma_chan *dma_chan_rx, *dma_chan_tx; struct scatterlist rx_sgl, tx_sgl[2]; void *rx_buf; - unsigned int rx_bytes, tx_bytes; - struct work_struct tsk_dma_rx, tsk_dma_tx; + unsigned int tx_bytes; unsigned int dma_tx_nents; wait_queue_head_t dma_wait; }; @@ -505,32 +504,23 @@ static void dma_tx_callback(void *data) dev_dbg(sport->port.dev, "exit in %s.\n", __func__); return; } - - schedule_work(&sport->tsk_dma_tx); } -static void dma_tx_work(struct work_struct *w) +static void imx_dma_tx(struct imx_port *sport) { - struct imx_port *sport = container_of(w, struct imx_port, tsk_dma_tx); struct circ_buf *xmit = &sport->port.state->xmit; struct scatterlist *sgl = sport->tx_sgl; struct dma_async_tx_descriptor *desc; struct dma_chan *chan = sport->dma_chan_tx; struct device *dev = sport->port.dev; enum dma_status status; - unsigned long flags; int ret; status = dmaengine_tx_status(chan, (dma_cookie_t)0, NULL); if (DMA_IN_PROGRESS == status) return; - spin_lock_irqsave(&sport->port.lock, flags); sport->tx_bytes = uart_circ_chars_pending(xmit); - if (sport->tx_bytes == 0) { - spin_unlock_irqrestore(&sport->port.lock, flags); - return; - } if (xmit->tail > xmit->head && xmit->head > 0) { sport->dma_tx_nents = 2; @@ -542,7 +532,6 @@ static void dma_tx_work(struct work_struct *w) sport->dma_tx_nents = 1; sg_init_one(sgl, xmit->buf + xmit->tail, sport->tx_bytes); } - spin_unlock_irqrestore(&sport->port.lock, flags); ret = dma_map_sg(dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE); if (ret == 0) { @@ -609,11 +598,7 @@ static void imx_start_tx(struct uart_port *port) } if (sport->dma_is_enabled) { - /* - * We may in the interrupt context, so arise a work_struct to - * do the real job. - */ - schedule_work(&sport->tsk_dma_tx); + imx_dma_tx(sport); return; } @@ -732,6 +717,7 @@ out: return IRQ_HANDLED; } +static int start_rx_dma(struct imx_port *sport); /* * If the RXFIFO is filled with some data, and then we * arise a DMA operation to receive them. @@ -750,7 +736,7 @@ static void imx_dma_rxint(struct imx_port *sport) writel(temp, sport->port.membase + UCR1); /* tell the DMA to receive the data. */ - schedule_work(&sport->tsk_dma_rx); + start_rx_dma(sport); } } @@ -872,22 +858,6 @@ static int imx_setup_ufcr(struct imx_port *sport, unsigned int mode) } #define RX_BUF_SIZE (PAGE_SIZE) -static int start_rx_dma(struct imx_port *sport); -static void dma_rx_work(struct work_struct *w) -{ - struct imx_port *sport = container_of(w, struct imx_port, tsk_dma_rx); - struct tty_port *port = &sport->port.state->port; - - if (sport->rx_bytes) { - tty_insert_flip_string(port, sport->rx_buf, sport->rx_bytes); - tty_flip_buffer_push(port); - sport->rx_bytes = 0; - } - - if (sport->dma_is_rxing) - start_rx_dma(sport); -} - static void imx_rx_dma_done(struct imx_port *sport) { unsigned long temp; @@ -919,6 +889,7 @@ static void dma_rx_callback(void *data) struct imx_port *sport = data; struct dma_chan *chan = sport->dma_chan_rx; struct scatterlist *sgl = &sport->rx_sgl; + struct tty_port *port = &sport->port.state->port; struct dma_tx_state state; enum dma_status status; unsigned int count; @@ -931,8 +902,10 @@ static void dma_rx_callback(void *data) dev_dbg(sport->port.dev, "We get %d bytes.\n", count); if (count) { - sport->rx_bytes = count; - schedule_work(&sport->tsk_dma_rx); + tty_insert_flip_string(port, sport->rx_buf, count); + tty_flip_buffer_push(port); + + start_rx_dma(sport); } else imx_rx_dma_done(sport); } @@ -1014,7 +987,6 @@ static int imx_uart_dma_init(struct imx_port *sport) ret = -ENOMEM; goto err; } - sport->rx_bytes = 0; /* Prepare for TX : */ sport->dma_chan_tx = dma_request_slave_channel(dev, "tx"); @@ -1045,11 +1017,7 @@ err: static void imx_enable_dma(struct imx_port *sport) { unsigned long temp; - struct tty_port *port = &sport->port.state->port; - port->low_latency = 1; - INIT_WORK(&sport->tsk_dma_tx, dma_tx_work); - INIT_WORK(&sport->tsk_dma_rx, dma_rx_work); init_waitqueue_head(&sport->dma_wait); /* set UCR1 */ @@ -1070,7 +1038,6 @@ static void imx_enable_dma(struct imx_port *sport) static void imx_disable_dma(struct imx_port *sport) { unsigned long temp; - struct tty_port *port = &sport->port.state->port; /* clear UCR1 */ temp = readl(sport->port.membase + UCR1); @@ -1088,7 +1055,6 @@ static void imx_disable_dma(struct imx_port *sport) writel(temp, sport->port.membase + UCR4); sport->dma_is_enabled = 0; - port->low_latency = 0; } /* half the RX buffer size */ -- 1.7.2.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
