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| author | Brant Merryman <brant.merryman@silabs.com> | 2020-06-26 07:24:20 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-21 10:48:14 +0300 |
| commit | b00b89e16ecf186153a5c62b15a940b991a6a3ef (patch) | |
| tree | e53e9f4fa540eb90dd953a492ab40683715493c4 /drivers/usb/serial/cp210x.c | |
| parent | bb70a1cbe5e470cf740f33091190b144c8a99461 (diff) | |
| download | linux-b00b89e16ecf186153a5c62b15a940b991a6a3ef.tar.xz | |
USB: serial: cp210x: re-enable auto-RTS on open
commit c7614ff9b73a1e6fb2b1b51396da132ed22fecdb upstream.
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: 39a66b8d22a3 ("[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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/serial/cp210x.c')
| -rw-r--r-- | drivers/usb/serial/cp210x.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index 8dd9852f399d..9ed3e0cc717e 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -925,6 +925,7 @@ 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); @@ -1025,6 +1026,22 @@ 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__); |