USB: serial: cp210x: re-enable auto-RTS on open (c7614ff9) · Commits · 戴 / test

CP210x hardware disables auto-RTS but leaves auto-CTS when in hardware flow control mode and UART on cp210x hardware is disabled. When re-opening the port, if auto-CTS is enabled on the cp210x, then auto-RTS must be re-enabled in the driver. Signed-off-by:

Brant Merryman <brant.merryman@silabs.com> Co-developed-by:

Phu Luu <phu.luu@silabs.com> Signed-off-by:

Phu Luu <phu.luu@silabs.com> Link: https://lore.kernel.org/r/ECCF8E73-91F3-4080-BE17-1714BC8818FB@silabs.com [ johan: fix up tags and problem description ] Fixes: ("[PATCH] USB: CP2101 Add support for flow control") Cc: stable <stable@vger.kernel.org> # 2.6.12 Signed-off-by:

Johan Hovold <johan@kernel.org>

drivers/usb/serial/cp210x.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -917,6 +917,7 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
		u32 baud;
		u16 bits;
		u32 ctl_hs;
		u32 flow_repl;

		cp210x_read_u32_reg(port, CP210X_GET_BAUDRATE, &baud);

		@@ -1017,6 +1018,22 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
		ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
		if (ctl_hs & CP210X_SERIAL_CTS_HANDSHAKE) {
		dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
		/*
		* When the port is closed, the CP210x hardware disables
		* auto-RTS and RTS is deasserted but it leaves auto-CTS when
		* in hardware flow control mode. When re-opening the port, if
		* auto-CTS is enabled on the cp210x, then auto-RTS must be
		* re-enabled in the driver.
		*/
		flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
		flow_repl &= ~CP210X_SERIAL_RTS_MASK;
		flow_repl \|= CP210X_SERIAL_RTS_SHIFT(CP210X_SERIAL_RTS_FLOW_CTL);
		flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
		cp210x_write_reg_block(port,
		CP210X_SET_FLOW,
		&flow_ctl,
		sizeof(flow_ctl));

		cflag \|= CRTSCTS;
		} else {
		dev_dbg(dev, "%s - flow control = NONE\n", __func__);

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