i use sam9g25 on my board. i couldn't tested of signal at txd3, when i enable serial DMA support by select [*] Atmel Serial DMA support in linux kernel menuconfig.
i try to slove the problem in several ways. it works when i change the atslave->cfg as below. anybody meet the same problem?


void __init at91_add_device_serial(void)
{
int i;

for (i = 0; i < ATMEL_MAX_UART; i++) {
if (at91_usarts[i]) {
#if defined(CONFIG_AT_HDMAC) || defined(CONFIG_AT_HDMAC_MODULE)
int peripheral_id = platform_get_irq(at91_usarts[i], 0);
struct atmel_uart_data *pdata = at91_usarts[i]->dev.platform_data;

if (pdata->use_dma_tx) {
struct at_dma_slave *atslave;

atslave = kzalloc(sizeof(struct at_dma_slave), GFP_KERNEL);

/* DMA slave channel configuration */
if (peripheral_id == AT91SAM9X5_ID_USART0
|| peripheral_id == AT91SAM9X5_ID_USART1
|| peripheral_id == AT91SAM9X5_ID_UART0)
atslave->dma_dev = &at_hdmac0_device.dev;
else
atslave->dma_dev = &at_hdmac1_device.dev;

atslave->reg_width = DW_DMA_SLAVE_WIDTH_8BIT;
#if 0
atslave->cfg = ATC_FIFOCFG_HALFFIFO
| ATC_SRC_H2SEL_SW | ATC_DST_H2SEL_HW
| (AT_DMA_ID_USART0_TX << 4); /*ATC_DST_PER(peripheral_id);*/

#endif
//
#if 1
atslave->cfg = ATC_FIFOCFG_HALFFIFO
| ATC_SRC_H2SEL_HW | ATC_DST_H2SEL_HW
| ATC_SRC_PER(AT_DMA_ID_USART3_RX)
| ATC_DST_PER(AT_DMA_ID_USART3_TX);

#endif
pdata->dma_tx_slave = atslave;
}
#endif
platform_device_register(at91_usarts[i]);
}
}

if (!atmel_default_console_device)
printk(KERN_INFO "AT91: No default serial console defined.\n");
}