linux-kernel - Re: [PATCH v4 06/13] USB: ch341: add support for parity, frame length, stop bits

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Date:	Fri, 29 Apr 2016 15:11:52 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Grigori Goronzy <greg@...wn.ath.cx>
Cc:	Johan Hovold <johan@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 06/13] USB: ch341: add support for parity, frame
 length, stop bits

On Fri, Apr 15, 2016 at 11:14:09PM +0200, Grigori Goronzy wrote:
> With the new reinitialization method, configuring parity, different
> frame lengths and different stop bit settings work as expected on
> both CH340G and CH341A.  This has been extensively tested with a
> logic analyzer.
> 
> v2: only set mark/space when parity is enabled, simplifications,
> patch termios HW flags.
> v3: fix parity odd/even regression.
> 
> Tested-by: Ryan Barber <rfb@...scraper.nu>
> Signed-off-by: Grigori Goronzy <greg@...wn.ath.cx>
> ---
>  drivers/usb/serial/ch341.c | 40 ++++++++++++++++++++++++++++++----------
>  1 file changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
> index 6181616..2fbec4a 100644
> --- a/drivers/usb/serial/ch341.c
> +++ b/drivers/usb/serial/ch341.c
> @@ -341,7 +341,6 @@ static void ch341_set_termios(struct tty_struct *tty,
>  		struct usb_serial_port *port, struct ktermios *old_termios)
>  {
>  	struct ch341_private *priv = usb_get_serial_port_data(port);
> -	unsigned baud_rate;
>  	unsigned long flags;
>  	unsigned char ctrl;
>  	int r;
> @@ -350,13 +349,39 @@ static void ch341_set_termios(struct tty_struct *tty,
>  	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
>  		return;
>  
> -	baud_rate = tty_get_baud_rate(tty);
> +	priv->baud_rate = tty_get_baud_rate(tty);
>  
> -	priv->baud_rate = baud_rate;

This is an unrelated change.

> +	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
>  
> -	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
> +	switch (C_CSIZE(tty)) {
> +	case CS5:
> +		ctrl |= CH341_LCR_CS5;
> +		break;
> +	case CS6:
> +		ctrl |= CH341_LCR_CS6;
> +		break;
> +	case CS7:
> +		ctrl |= CH341_LCR_CS7;
> +		break;
> +	default:
> +		tty->termios.c_cflag |= CS8;

CSIZE is 2-bits wide, so this shouldn't be needed. (If it were, you'd
need to clear the bits first.)

> +	case CS8:
> +		ctrl |= CH341_LCR_CS8;
> +		break;
> +	}
> +
> +	if (C_PARENB(tty)) {
> +		ctrl |= CH341_LCR_ENABLE_PAR;
> +		if (C_PARODD(tty) == 0)
> +			ctrl |= CH341_LCR_PAR_EVEN;
> +		if (C_CMSPAR(tty))
> +			ctrl |= CH341_LCR_MARK_SPACE;
> +	}
> +
> +	if (C_CSTOPB(tty))
> +		ctrl |= CH341_LCR_STOP_BITS_2;
>  
> -	if (baud_rate) {
> +	if (priv->baud_rate) {
>  		spin_lock_irqsave(&priv->lock, flags);
>  		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
>  		spin_unlock_irqrestore(&priv->lock, flags);
> @@ -373,11 +398,6 @@ static void ch341_set_termios(struct tty_struct *tty,
>  
>  	ch341_set_handshake(port->serial->dev, priv->line_control);
>  
> -	/* Unimplemented:
> -	 * (cflag & CSIZE) : data bits [5, 8]
> -	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
> -	 * (cflag & CSTOPB) : stop bits [1, 2]
> -	 */
>  }
>  
>  static void ch341_break_ctl(struct tty_struct *tty, int break_state)

Looks good otherwise.

Thanks,
Johan