From: Jon Hunter <jon-hunter@xxxxxx> When using DMA there are two timeouts defined. The first timeout, rx_timeout, is really a polling rate in which software polls the DMA status to see if the DMA has finished. This is necessary for the RX side because we do not know how much data we will receive. The secound timeout, RX_TIMEOUT, is a timeout after which the DMA will be stopped if no more data is received. To make this clearer, rename rx_timeout as rx_poll_rate and rename the function serial_omap_rx_timeout() to serial_omap_rxdma_poll(). The OMAP-Serial driver defines an RX_TIMEOUT of 3 seconds that is used to indicate when the DMA for UART can be stopped if no more data is received. The value is a global definition that is applied to all instances of the UART. Each UART may be used for a different purpose and so the timeout required may differ. Make this value configurable for each UART so that this value can be optimised for power savings. Acked-by: Kevin Hilman <khilman@xxxxxx> Signed-off-by: Jon Hunter <jon-hunter@xxxxxx> Signed-off-by: Govindraj.R <govindraj.raja@xxxxxx> --- This patch is derived from a custom 2.6.35 kernel Available here: http://git.omapzoom.org/?p=kernel/omap.git;a=commitdiff; h=b47839fb84e68333ea29a327cf5aa694b71be7d6; hp=f62f570e8580507be48ad004defc2ec714b6e05d arch/arm/mach-omap2/serial.c | 5 ++++- arch/arm/plat-omap/include/plat/omap-serial.h | 3 ++- drivers/tty/serial/omap-serial.c | 15 ++++++++------- 3 files changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c index 0e45d9a..57d063a 100644 --- a/arch/arm/mach-omap2/serial.c +++ b/arch/arm/mach-omap2/serial.c @@ -53,13 +53,15 @@ static u8 num_uarts; -#define DEFAULT_RXDMA_TIMEOUT 1 /* RX DMA polling rate (us) */ +#define DEFAULT_RXDMA_POLLRATE 1 /* RX DMA polling rate (us) */ #define DEFAULT_RXDMA_BUFSIZE 4096 /* RX DMA buffer size */ +#define DEFAULT_RXDMA_TIMEOUT (3 * HZ)/* RX DMA timeout (jiffies) */ static struct omap_uart_port_info omap_serial_default_info[] = { { .dma_enabled = 0, .dma_rx_buf_size = DEFAULT_RXDMA_BUFSIZE, + .dma_rx_poll_rate = DEFAULT_RXDMA_POLLRATE, .dma_rx_timeout = DEFAULT_RXDMA_TIMEOUT, .autosuspend_timeout = DEFAULT_AUTOSUSPEND_DELAY, }, @@ -338,6 +340,7 @@ void __init omap_serial_init_port(struct omap_board_data *bdata, pdata->set_force_idle = omap_uart_set_forceidle; pdata->dma_enabled = info->dma_enabled; pdata->dma_rx_buf_size = info->dma_rx_buf_size; + pdata->dma_rx_poll_rate = info->dma_rx_poll_rate; pdata->dma_rx_timeout = info->dma_rx_timeout; pdata->autosuspend_timeout = info->autosuspend_timeout; diff --git a/arch/arm/plat-omap/include/plat/omap-serial.h b/arch/arm/plat-omap/include/plat/omap-serial.h index a40a41a..28abc6b 100644 --- a/arch/arm/plat-omap/include/plat/omap-serial.h +++ b/arch/arm/plat-omap/include/plat/omap-serial.h @@ -51,7 +51,6 @@ #define OMAP_UART_DMA_CH_FREE -1 -#define RX_TIMEOUT (3 * HZ) #define OMAP_MAX_HSUART_PORTS 4 #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA @@ -67,6 +66,7 @@ struct omap_uart_port_info { unsigned int dma_rx_buf_size; unsigned int dma_rx_timeout; unsigned int autosuspend_timeout; + unsigned int dma_rx_poll_rate; void (*enable_wakeup)(struct platform_device *, bool); u32 (*get_context_loss_count)(struct device *); @@ -95,6 +95,7 @@ struct uart_omap_dma { /* timer to poll activity on rx dma */ struct timer_list rx_timer; unsigned int rx_buf_size; + unsigned int rx_poll_rate; unsigned int rx_timeout; }; diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 15e0655..64e4ab5 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -47,7 +47,7 @@ static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS]; /* Forward declaration of functions */ static void uart_tx_dma_callback(int lch, u16 ch_status, void *data); -static void serial_omap_rx_timeout(unsigned long uart_no); +static void serial_omap_rxdma_poll(unsigned long uart_no); static int serial_omap_start_rxdma(struct uart_omap_port *up); static void serial_omap_mdr1_errataset(struct uart_omap_port *up, u8 mdr1); @@ -542,7 +542,7 @@ static int serial_omap_startup(struct uart_port *port) (dma_addr_t *)&(up->uart_dma.tx_buf_dma_phys), 0); init_timer(&(up->uart_dma.rx_timer)); - up->uart_dma.rx_timer.function = serial_omap_rx_timeout; + up->uart_dma.rx_timer.function = serial_omap_rxdma_poll; up->uart_dma.rx_timer.data = up->pdev->id; /* Currently the buffer size is 4KB. Can increase it */ up->uart_dma.rx_buf = dma_alloc_coherent(NULL, @@ -1147,7 +1147,7 @@ static int serial_omap_resume(struct device *dev) return 0; } -static void serial_omap_rx_timeout(unsigned long uart_no) +static void serial_omap_rxdma_poll(unsigned long uart_no) { struct uart_omap_port *up = ui[uart_no]; unsigned int curr_dma_pos, curr_transmitted_size; @@ -1157,9 +1157,9 @@ static void serial_omap_rx_timeout(unsigned long uart_no) if ((curr_dma_pos == up->uart_dma.prev_rx_dma_pos) || (curr_dma_pos == 0)) { if (jiffies_to_msecs(jiffies - up->port_activity) < - RX_TIMEOUT) { + up->uart_dma.rx_timeout) { mod_timer(&up->uart_dma.rx_timer, jiffies + - usecs_to_jiffies(up->uart_dma.rx_timeout)); + usecs_to_jiffies(up->uart_dma.rx_poll_rate)); } else { serial_omap_stop_rxdma(up); up->ier |= (UART_IER_RDI | UART_IER_RLSI); @@ -1188,7 +1188,7 @@ static void serial_omap_rx_timeout(unsigned long uart_no) } } else { mod_timer(&up->uart_dma.rx_timer, jiffies + - usecs_to_jiffies(up->uart_dma.rx_timeout)); + usecs_to_jiffies(up->uart_dma.rx_poll_rate)); } up->port_activity = jiffies; } @@ -1227,7 +1227,7 @@ static int serial_omap_start_rxdma(struct uart_omap_port *up) /* FIXME: Cache maintenance needed here? */ omap_start_dma(up->uart_dma.rx_dma_channel); mod_timer(&up->uart_dma.rx_timer, jiffies + - usecs_to_jiffies(up->uart_dma.rx_timeout)); + usecs_to_jiffies(up->uart_dma.rx_poll_rate)); up->uart_dma.rx_dma_used = true; return ret; } @@ -1364,6 +1364,7 @@ static int serial_omap_probe(struct platform_device *pdev) up->use_dma = 1; up->uart_dma.rx_buf_size = omap_up_info->dma_rx_buf_size; up->uart_dma.rx_timeout = omap_up_info->dma_rx_timeout; + up->uart_dma.rx_poll_rate = omap_up_info->dma_rx_poll_rate; spin_lock_init(&(up->uart_dma.tx_lock)); spin_lock_init(&(up->uart_dma.rx_lock)); up->uart_dma.tx_dma_channel = OMAP_UART_DMA_CH_FREE; -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
