This is a note to let you know that I've just added the patch titled
serial: 8250_mtk: fix uart corruption issue when rx power off
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-8250_mtk-fix-uart-corruption-issue-when-rx-power-off.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7c4a509d3815a260c423c0633bd73695250ac26d Mon Sep 17 00:00:00 2001
From: Zhiyong Tao <zhiyong.tao@xxxxxxxxxxxx>
Date: Thu, 29 Jul 2021 16:46:40 +0800
Subject: serial: 8250_mtk: fix uart corruption issue when rx power off
From: Zhiyong Tao <zhiyong.tao@xxxxxxxxxxxx>
commit 7c4a509d3815a260c423c0633bd73695250ac26d upstream.
Fix uart corruption issue when rx power off.
Add spin lock in mtk8250_dma_rx_complete function in APDMA mode.
when uart is used as a communication port with external device(GPS).
when external device(GPS) power off, the power of rx pin is also from
1.8v to 0v. Even if there is not any data in rx. But uart rx pin can
capture the data "0".
If uart don't receive any data in specified cycle, uart will generates
BI(Break interrupt) interrupt.
If external device(GPS) power off, we found that BI interrupt appeared
continuously and very frequently.
When uart interrupt type is BI, uart IRQ handler(8250 framwork
API:serial8250_handle_irq) will push data to tty buffer.
mtk8250_dma_rx_complete is a task of mtk_uart_apdma_rx_handler.
mtk8250_dma_rx_complete priority is lower than uart irq
handler(serial8250_handle_irq).
if we are in process of mtk8250_dma_rx_complete, uart appear BI
interrupt:1)serial8250_handle_irq will priority execution.2)it may cause
write tty buffer conflict in mtk8250_dma_rx_complete.
So the spin lock protect the rx receive data process is not break.
Signed-off-by: Zhiyong Tao <zhiyong.tao@xxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210729084640.17613-2-zhiyong.tao@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_mtk.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -93,10 +93,13 @@ static void mtk8250_dma_rx_complete(void
struct dma_tx_state state;
int copied, total, cnt;
unsigned char *ptr;
+ unsigned long flags;
if (data->rx_status == DMA_RX_SHUTDOWN)
return;
+ spin_lock_irqsave(&up->port.lock, flags);
+
dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
total = dma->rx_size - state.residue;
cnt = total;
@@ -120,6 +123,8 @@ static void mtk8250_dma_rx_complete(void
tty_flip_buffer_push(tty_port);
mtk8250_rx_dma(up);
+
+ spin_unlock_irqrestore(&up->port.lock, flags);
}
static void mtk8250_rx_dma(struct uart_8250_port *up)
Patches currently in stable-queue which might be from zhiyong.tao@xxxxxxxxxxxx are
queue-5.13/serial-8250_mtk-fix-uart-corruption-issue-when-rx-power-off.patch
