struct dw8250_port_data *pd = p->private_data;
struct dw8250_data *data = to_dw8250_data(pd);
struct uart_8250_port *up = up_to_u8250p(p);
- u32 reg;
+ u32 reg, old_dlf;
pd->hw_rs485_support = dw8250_detect_rs485_hw(p);
if (pd->hw_rs485_support) {
dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);
+ /* Preserve value written by firmware or bootloader */
+ old_dlf = dw8250_readl_ext(p, DW_UART_DLF);
dw8250_writel_ext(p, DW_UART_DLF, ~0U);
reg = dw8250_readl_ext(p, DW_UART_DLF);
- dw8250_writel_ext(p, DW_UART_DLF, 0);
+ dw8250_writel_ext(p, DW_UART_DLF, old_dlf);
if (reg) {
pd->dlf_size = fls(reg);