From: Bich Hemon <bich.hemon@xxxxxx>
Two improvements for dma receive in this patch:
- usart dma receiver (DMAR) is disabled during receive
- dma receive buffer is sync-ed for cpu before reading
and given back to the dma just after
Signed-off-by: Gerald Baeza <gerald.baeza@xxxxxx>
---
drivers/tty/serial/stm32-usart.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 266dc4f..13fc520 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -393,11 +393,21 @@ static irqreturn_t stm32_threaded_interrupt(int irq, void *ptr)
{
struct uart_port *port = ptr;
struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
spin_lock(&port->lock);
- if (stm32_port->rx_ch)
+ if (stm32_port->rx_ch) {
+ stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
+ dma_sync_single_for_cpu(port->dev,
+ stm32_port->rx_dma_buf,
+ RX_BUF_L, DMA_FROM_DEVICE);
stm32_receive_chars(port, true);
+ dma_sync_single_for_device(port->dev,
+ stm32_port->rx_dma_buf,
+ RX_BUF_L, DMA_FROM_DEVICE);
+ stm32_set_bits(port, ofs->cr3, USART_CR3_DMAR);
+ }
spin_unlock(&port->lock);
--
1.9.1
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