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[V2] tty: serial: fsl_lpuart: Clear the error flags by writing 1 for lpuart32 platforms

Message ID 20230801022304.24251-1-sherry.sun@nxp.com
State New
Headers show
Series [V2] tty: serial: fsl_lpuart: Clear the error flags by writing 1 for lpuart32 platforms | expand

Commit Message

Sherry Sun Aug. 1, 2023, 2:23 a.m. UTC 
Do not read the data register to clear the error flags for lpuart32
platforms, the additional read may cause the receive FIFO underflow
since the DMA has already read the data register.
Actually all lpuart32 platforms support write 1 to clear those error
bits, let's use this method to better clear the error flags.

Fixes: 42b68768e51b ("serial: fsl_lpuart: DMA support for 32-bit variant")
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
---
Changes in V2:
1. Improve commit message to avoid confusion as commented by Jiri.
---
 drivers/tty/serial/fsl_lpuart.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f6644c5989d3..f72e1340b47d 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1120,8 +1120,8 @@  static void lpuart_copy_rx_to_tty(struct lpuart_port *sport)
 		unsigned long sr = lpuart32_read(&sport->port, UARTSTAT);
 
 		if (sr & (UARTSTAT_PE | UARTSTAT_FE)) {
-			/* Read DR to clear the error flags */
-			lpuart32_read(&sport->port, UARTDATA);
+			/* Clear the error flags */
+			lpuart32_write(&sport->port, sr, UARTSTAT);
 
 			if (sr & UARTSTAT_PE)
 				sport->port.icount.parity++;