linux-kernel - Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity

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Message-ID: <55D20AB4.4030405@hurleysoftware.com>
Date:	Mon, 17 Aug 2015 12:24:20 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Anirudha Sarangi <anirudha.sarangi@...inx.com>,
	Michal Simek <michals@...inx.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"monstr@...str.eu" <monstr@...str.eu>,
	Soren Brinkmann <sorenb@...inx.com>,
	Jiri Slaby <jslaby@...e.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd
 parity

On 08/17/2015 11:55 AM, Anirudha Sarangi wrote:
> Hi,
> 
>> -----Original Message-----
>> From: Peter Hurley [mailto:peter@...leysoftware.com]
>> Sent: Monday, August 17, 2015 9:09 PM
>> To: Michal Simek
>> Cc: linux-kernel@...r.kernel.org; monstr@...str.eu; Anirudha Sarangi; Soren
>> Brinkmann; Jiri Slaby; linux-serial@...r.kernel.org; Greg Kroah-Hartman; linux-
>> arm-kernel@...ts.infradead.org
>> Subject: Re: [PATCH 1/4] serial: xuartps: Fix termios issue for enabling odd parity
>>
>> On 08/17/2015 03:22 AM, Michal Simek wrote:
>>> From: Anirudha Sarangi <anirudha.sarangi@...inx.com>
>>>
>>> Existing set_termios does not handle the option for enabling odd
>>> parity. This patch fixes it.
>>
>> NAK. PARODD does not enable parity generation or detection.
>>
> What if someone is trying to change from even to odd parity?

If userspace wants odd parity, then c_cflag must have both
PARENB and PARODD set.

Just PARODD does nothing.

>From SUS v4, General Terminal Interface, 11.2.4 Control Modes;

"If PARENB is set, parity generation and detection shall be enabled
and a parity bit is added to each byte. If parity is enabled, PARODD
shall specify odd parity if set; otherwise, even parity shall be used."



> In this conditional case, we setup some register bit for the same.
> Is the above use case not a valid one?
> 
> Regards
> Anirudha
> 
>> Regards,
>> Peter Hurley
>>
>>> Signed-off-by: Anirudha Sarangi <anirudh@...inx.com>
>>> Signed-off-by: Michal Simek <michal.simek@...inx.com>
>>> ---
>>>
>>>  drivers/tty/serial/xilinx_uartps.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/tty/serial/xilinx_uartps.c
>>> b/drivers/tty/serial/xilinx_uartps.c
>>> index 009e0dbc12d2..a3020344ac9d 100644
>>> --- a/drivers/tty/serial/xilinx_uartps.c
>>> +++ b/drivers/tty/serial/xilinx_uartps.c
>>> @@ -723,7 +723,7 @@ static void cdns_uart_set_termios(struct uart_port
>> *port,
>>>     else
>>>             cval |= CDNS_UART_MR_STOPMODE_1_BIT; /* 1 STOP bit */
>>>
>>> -   if (termios->c_cflag & PARENB) {
>>> +   if ((termios->c_cflag & PARENB) || (termios->c_cflag & PARODD)) {
>>>             /* Mark or Space parity */
>>>             if (termios->c_cflag & CMSPAR) {
>>>                     if (termios->c_cflag & PARODD)
>>>
> 
> 
> 
> This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.
> 

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