linux-kernel - Re: [PATCH v3 06/13] USB: ch341: add support for parity, frame length, stop bits

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Date:	Mon, 11 Apr 2016 20:25:22 +0200
From:	Grigori Goronzy <greg@...wn.ath.cx>
To:	Karl Palsson <karlp@...ak.net.au>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Johan Hovold <johan@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v3 06/13] USB: ch341: add support for parity, frame
 length, stop bits

On 2016-04-11 19:25, Karl Palsson wrote:
> Sorry if you get this twice, I was having some client problems,
> but wanted to make sure you got this one...
> 
> 
> Grigori Goronzy <greg@...wn.ath.cx> 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.
>> 
>> 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..99b4621 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;
>> +	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;
>> +	case CS8:
>> +		ctrl |= CH341_LCR_CS8;
>> +		break;
>> +	}
>> +
>> +	if (C_PARENB(tty)) {
>> +		ctrl |= CH341_LCR_ENABLE_PAR;
>> +		if (C_PARODD(tty))
>> +			ctrl |= CH341_LCR_PAR_EVEN;
> 
> Are you sure this does the right thing now? this is, as best as I
> can tell, the inverse of what you had earlier, and doesn't read
> right, if this is working, then I suggest renaming _LCR_PAR_EVEN
> to LCR_PAR_ODD?
> 

No, this is absolutely wrong, of course.  I only did some sporadic 
testing because my refactoring wasn't supposed to change functionality.  
Thanks for pointing it out!

Grigori