[PATCH 2/2] serial: fsl_lpuart: calculate DMA burst
From: stefan@agner.ch (Stefan Agner)
Date: 2014-07-02 16:02:57
Also in:
linux-serial
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
The DMA burst size must match the transmit FIFO depth in order to make sure all character are transmitted. This patch calculates DMA burst size by using FIFO depth rather than use the hardcoded 16 bytes. This is required since some UARTs (e.g. UART2 on Vybrid) have a FIFO depth of 8 bytes. Signed-off-by: Stefan Agner <stefan@agner.ch> --- drivers/tty/serial/fsl_lpuart.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 6b462a9..f973456 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c@@ -117,8 +117,6 @@ #define UARTSFIFO_TXOF 0x02 #define UARTSFIFO_RXUF 0x01 -#define DMA_MAXBURST 16 -#define DMA_MAXBURST_MASK (DMA_MAXBURST - 1) #define FSL_UART_RX_DMA_BUFFER_SIZE 64 #define DRIVER_NAME "fsl-lpuart"
@@ -240,7 +238,7 @@ static int lpuart_dma_tx(struct lpuart_port *sport, unsigned long count) dma_sync_single_for_device(sport->port.dev, sport->dma_tx_buf_bus, UART_XMIT_SIZE, DMA_TO_DEVICE); - sport->dma_tx_bytes = count & ~(DMA_MAXBURST_MASK); + sport->dma_tx_bytes = count & ~(sport->txfifo_size - 1); tx_bus_addr = sport->dma_tx_buf_bus + xmit->tail; sport->dma_tx_desc = dmaengine_prep_slave_single(sport->dma_tx_chan, tx_bus_addr, sport->dma_tx_bytes,
@@ -269,7 +267,7 @@ static void lpuart_prepare_tx(struct lpuart_port *sport) if (!count) return; - if (count < DMA_MAXBURST) + if (count < sport->txfifo_size) writeb(readb(sport->port.membase + UARTCR5) & ~UARTCR5_TDMAS, sport->port.membase + UARTCR5); else {
@@ -599,15 +597,7 @@ static void lpuart_setup_watermark(struct lpuart_port *sport) UARTCR2_RIE | UARTCR2_RE); writeb(cr2, sport->port.membase + UARTCR2); - /* determine FIFO size and enable FIFO mode */ val = readb(sport->port.membase + UARTPFIFO); - - sport->txfifo_size = 0x1 << (((val >> UARTPFIFO_TXSIZE_OFF) & - UARTPFIFO_FIFOSIZE_MASK) + 1); - - sport->rxfifo_size = 0x1 << (((val >> UARTPFIFO_RXSIZE_OFF) & - UARTPFIFO_FIFOSIZE_MASK) + 1); - writeb(val | UARTPFIFO_TXFE | UARTPFIFO_RXFE, sport->port.membase + UARTPFIFO);
@@ -652,7 +642,7 @@ static int lpuart_dma_tx_request(struct uart_port *port) dma_buf = sport->port.state->xmit.buf; dma_tx_sconfig.dst_addr = sport->port.mapbase + UARTDR; dma_tx_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; - dma_tx_sconfig.dst_maxburst = DMA_MAXBURST; + dma_tx_sconfig.dst_maxburst = sport->txfifo_size; dma_tx_sconfig.direction = DMA_MEM_TO_DEV; ret = dmaengine_slave_config(tx_chan, &dma_tx_sconfig);
@@ -765,7 +755,16 @@ static int lpuart_startup(struct uart_port *port) unsigned long flags; unsigned char temp; - /*whether use dma support by dma request results*/ + /* determine FIFO size and enable FIFO mode */ + temp = readb(sport->port.membase + UARTPFIFO); + + sport->txfifo_size = 0x1 << (((temp >> UARTPFIFO_TXSIZE_OFF) & + UARTPFIFO_FIFOSIZE_MASK) + 1); + + sport->rxfifo_size = 0x1 << (((temp >> UARTPFIFO_RXSIZE_OFF) & + UARTPFIFO_FIFOSIZE_MASK) + 1); + + /* Whether use dma support by dma request results */ if (lpuart_dma_tx_request(port) || lpuart_dma_rx_request(port)) { sport->lpuart_dma_use = false; } else {
--
2.0.1