diff options
| -rw-r--r-- | drivers/tty/serial/imx.c | 63 |
1 files changed, 49 insertions, 14 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 4167b61bf4e0..33509b4beaec 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -719,6 +719,27 @@ out: return IRQ_HANDLED; } +static void imx_disable_rx_int(struct imx_port *sport) +{ + unsigned long temp; + + sport->dma_is_rxing = 1; + + /* disable the receiver ready and aging timer interrupts */ + temp = readl(sport->port.membase + UCR1); + temp &= ~(UCR1_RRDYEN); + writel(temp, sport->port.membase + UCR1); + + temp = readl(sport->port.membase + UCR2); + temp &= ~(UCR2_ATEN); + writel(temp, sport->port.membase + UCR2); + + /* disable the rx errors interrupts */ + temp = readl(sport->port.membase + UCR4); + temp &= ~UCR4_OREN; + writel(temp, sport->port.membase + UCR4); +} + static void clear_rx_errors(struct imx_port *sport); static int start_rx_dma(struct imx_port *sport); /* @@ -734,21 +755,8 @@ static void imx_dma_rxint(struct imx_port *sport) temp = readl(sport->port.membase + USR2); if ((temp & USR2_RDR) && !sport->dma_is_rxing) { - sport->dma_is_rxing = 1; - /* disable the receiver ready and aging timer interrupts */ - temp = readl(sport->port.membase + UCR1); - temp &= ~(UCR1_RRDYEN); - writel(temp, sport->port.membase + UCR1); - - temp = readl(sport->port.membase + UCR2); - temp &= ~(UCR2_ATEN); - writel(temp, sport->port.membase + UCR2); - - /* disable the rx errors interrupts */ - temp = readl(sport->port.membase + UCR4); - temp &= ~UCR4_OREN; - writel(temp, sport->port.membase + UCR4); + imx_disable_rx_int(sport); /* tell the DMA to receive the data. */ start_rx_dma(sport); @@ -1330,6 +1338,33 @@ static int imx_startup(struct uart_port *port) * Enable modem status interrupts */ imx_enable_ms(&sport->port); + + /* + * If the serial port is opened for reading start RX DMA immediately + * instead of waiting for RX FIFO interrupts. In our iMX53 the average + * delay for the first reception dropped from approximately 35000 + * microseconds to 1000 microseconds. + */ + if (sport->dma_is_enabled) { + struct tty_struct *tty = sport->port.state->port.tty; + struct tty_file_private *file_priv; + int readcnt = 0; + + spin_lock(&tty->files_lock); + + if (!list_empty(&tty->tty_files)) + list_for_each_entry(file_priv, &tty->tty_files, list) + if (!(file_priv->file->f_flags & O_WRONLY)) + readcnt++; + + spin_unlock(&tty->files_lock); + + if (readcnt > 0) { + imx_disable_rx_int(sport); + start_rx_dma(sport); + } + } + spin_unlock_irqrestore(&sport->port.lock, flags); return 0; |