From 002eb41f303e007011aecba25ea6de25a4ed475f Mon Sep 17 00:00:00 2001 From: Charanya Venkatraman Date: Tue, 7 Jun 2016 15:58:41 +0530 Subject: [PATCH] tty:serial:msm:Do not restore Rx interrupts in DMA Avoid data corruption issues that result in CRC errors during file transfers over serial ports at higher baud rates. The current msm_serial driver masks the FIFO Rx interrupts in msm_start_rx_dma() since Rx FIFO interrupts are not required in DMA mode. However, msm_complete_rx_dma() re-enables the Rx FIFO interrupts which could cause RXSTALE event to be processed when a TXLEV interrupt occurs. The following is the sequence of events that could occur resulting in data corruption. msm_start_rx_dma -> msm_complete_rx_dma --> spin_unlock_irqrestore(&port->lock) --> msm_uart_irq()(For TXLEV interrupt) --> msm_handle_rx_dm() (Read from FIFO resulting in data corruption) The patch fixes the issue by not restoring the RXLEV and RXSTALE interrupts in msm_complete_rx_dma(). These interrupts are required only in FIFO mode. Signed-off-by: Charanya Venkatraman Acked-by: Andy Gross Reviewed-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/msm_serial.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 88af5a3d21dd..d0384d4cccb1 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -557,10 +557,6 @@ static void msm_complete_rx_dma(void *args) val &= ~dma->enable_bit; msm_write(port, val, UARTDM_DMEN); - /* Restore interrupts */ - msm_port->imr |= UART_IMR_RXLEV | UART_IMR_RXSTALE; - msm_write(port, msm_port->imr, UART_IMR); - if (msm_read(port, UART_SR) & UART_SR_OVERRUN) { port->icount.overrun++; tty_insert_flip_char(tport, 0, TTY_OVERRUN); -- 2.45.2