From: Bich Hemon <bich.he...@st.com>
When stm32 dma is used, Data register has to be read in order
to clear the RXNE interrupt in case we received data before
usart probe.
Signed-off-by: Bich Hemon <bich.he...@st.com>
---
drivers/tty/serial/stm32-usart.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 06a92c8..b1f3aab 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -568,9 +568,18 @@ static int stm32_startup(struct uart_port *port)
struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
struct stm32_usart_config *cfg = &stm32_port->info->cfg;
const char *name = to_platform_device(port->dev)->name;
- u32 val;
+ u32 val, sr, dr;
int ret;
+ sr = readl_relaxed(port->membase + ofs->isr);
+
+ if ((sr & USART_SR_RXNE) && (stm32_port->rx_ch))
+ ret = readl_relaxed_poll_timeout_atomic(port->membase +
+ ofs->rdr,
+ dr,
+ !(sr & USART_SR_RXNE),
+ 10, 100000);
+
ret = request_threaded_irq(port->irq, stm32_interrupt,
stm32_threaded_interrupt,
IRQF_NO_SUSPEND, name, port);
--
1.9.1
