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From:   Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
To:     jorge.ramirez-ortiz@linaro.org, agross@kernel.org,
        david.brown@linaro.org, gregkh@linuxfoundation.org
Cc:     jslaby@suse.com, keescook@chromium.org, anton@enomsg.org,
        ccross@android.com, tony.luck@intel.com,
        linux-arm-msm@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-kernel@vger.kernel.org, khasim.mohammed@linaro.org,
        agsumit@qti.qualcomm.com
Subject: [PATCH] tty: serial: msm_serial: Fix XON/XOFF
Date:   Mon, 20 May 2019 12:34:35 +0200
Message-Id: <20190520103435.30850-1-jorge.ramirez-ortiz@linaro.org>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When the tty layer requests the uart to throttle, the current code
executing in msm_serial will trigger "Bad mode in Error Handler" and
generate an invalid stack frame in pstore before rebooting (that is if
pstore is indeed configured: otherwise the user shall just notice a
reboot with no further information dumped to the console).

This patch replaces the PIO byte accessor with the word accessor
already used in PIO mode.

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
---
 drivers/tty/serial/msm_serial.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 109096033bb1..23833ad952ba 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -860,6 +860,7 @@ static void msm_handle_tx(struct uart_port *port)
 	struct circ_buf *xmit = &msm_port->uart.state->xmit;
 	struct msm_dma *dma = &msm_port->tx_dma;
 	unsigned int pio_count, dma_count, dma_min;
+	char buf[4] = { 0 };
 	void __iomem *tf;
 	int err = 0;
 
@@ -869,10 +870,12 @@ static void msm_handle_tx(struct uart_port *port)
 		else
 			tf = port->membase + UART_TF;
 
+		buf[0] = port->x_char;
+
 		if (msm_port->is_uartdm)
 			msm_reset_dm_count(port, 1);
 
-		iowrite8_rep(tf, &port->x_char, 1);
+		iowrite32_rep(tf, buf, 1);
 		port->icount.tx++;
 		port->x_char = 0;
 		return;
-- 
2.21.0