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Commit 20258b32 authored by Jorge Ramirez-Ortiz's avatar Jorge Ramirez-Ortiz Committed by Greg Kroah-Hartman
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tty: serial: msm_serial: avoid system lockup condition 



[ Upstream commit ba3684f99f1b25d2a30b6956d02d339d7acb9799 ]

The function msm_wait_for_xmitr can be taken with interrupts
disabled. In order to avoid a potential system lockup - demonstrated
under stress testing conditions on SoC QCS404/5 - make sure we wait
for a bounded amount of time.

Tested on SoC QCS404.

Signed-off-by: default avatarJorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 483aca92

drivers/tty/serial/msm_serial.c

+4 −0
Original line number Diff line number Diff line
@@ -391,10 +391,14 @@ static void msm_request_rx_dma(struct msm_port *msm_port, resource_size_t base) 


static inline void msm_wait_for_xmitr(struct uart_port *port)

{

	unsigned int timeout = 500000;



	while (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY)) {

		if (msm_read(port, UART_ISR) & UART_ISR_TX_READY)

			break;

		udelay(1);

		if (!timeout--)

			break;

	}

	msm_write(port, UART_CR_CMD_RESET_TX_READY, UART_CR);

}