serial: imx: protect Soft Reset of port with lock (53794183) · Commits · 戴 / test

Previously Soft Reset (clear of SRST bit in UCR2 register) of UART in startup is not protected by lock, which may have race with console_write, as console_write may occur at anytime even when UART port is shutdown. To avoid this race, protect Soft reset of UART port with spin_lock. Signed-off-by:

Jiada Wang <jiada_wang@mentor.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -1114,6 +1114,12 @@ static int imx_startup(struct uart_port *port)

		writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);

		/* Can we enable the DMA support? */
		if (is_imx6q_uart(sport) && !uart_console(port) &&
		!sport->dma_is_inited)
		imx_uart_dma_init(sport);

		spin_lock_irqsave(&sport->port.lock, flags);
		/* Reset fifo's and state machines */
		i = 100;

		@@ -1124,13 +1130,6 @@ static int imx_startup(struct uart_port *port)
		while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) && (--i > 0))
		udelay(1);

		/* Can we enable the DMA support? */
		if (is_imx6q_uart(sport) && !uart_console(port) &&
		!sport->dma_is_inited)
		imx_uart_dma_init(sport);

		spin_lock_irqsave(&sport->port.lock, flags);

		/*
		* Finally, clear and enable interrupts
		*/

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