From: Johan Hovold <johan@kernel.org> stable inclusion from stable-v5.10.142 commit 2058aab4e3060ae239e3f2edd1d7aa66762c49c5 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6CSFH Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 41ca302a697b64a3dab4676e01d0d11bb184737d upstream. At least one older CH341 appears to have the RX timer enable bit inverted so that setting it disables the RX timer and prevents the FIFO from emptying until it is full. Only set the RX timer enable bit for devices with version newer than 0x27 (even though this probably affects all pre-0x30 devices). Reported-by: Jonathan Woithe <jwoithe@just42.net> Tested-by: Jonathan Woithe <jwoithe@just42.net> Link: https://lore.kernel.org/r/Ys1iPTfiZRWj2gXs@marvin.atrad.com.au Fixes: 4e46c410e050 ("USB: serial: ch341: reinitialize chip on reconfiguration") Cc: stable@vger.kernel.org # 4.10 Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com> --- drivers/usb/serial/ch341.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c index 3d05e22d25ae..97a250e75ab7 100644 --- a/drivers/usb/serial/ch341.c +++ b/drivers/usb/serial/ch341.c @@ -259,8 +259,12 @@ static int ch341_set_baudrate_lcr(struct usb_device *dev, /* * CH341A buffers data until a full endpoint-size packet (32 bytes) * has been received unless bit 7 is set. + * + * At least one device with version 0x27 appears to have this bit + * inverted. */ - val |= BIT(7); + if (priv->version > 0x27) + val |= BIT(7); r = ch341_control_out(dev, CH341_REQ_WRITE_REG, CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER, -- 2.25.1