* [PATCH] tty: serial: 8250_mtk: Fix quot calculation
@ 2014-10-09 16:23 Matthias Brugger
2014-10-09 21:52 ` Greg KH
0 siblings, 1 reply; 5+ messages in thread
From: Matthias Brugger @ 2014-10-09 16:23 UTC (permalink / raw)
To: gregkh
Cc: linux-kernel, jslaby, matthias.bgg, heiko, yingjoe.chen,
ibanezchen, linux-serial
The calculation of value quot for highspeed register set to three
was wrong. This patch fixes the calculation so that the serial port
for baudrates bigger then 576000 baud is working correctly.
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
---
drivers/tty/serial/8250/8250_mtk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index 1c4b4bf..4376c48 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
/* Set to highest baudrate supported */
if (baud >= 1152000)
baud = 921600;
- quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
+ quot = (port->uartclk / (256 * baud)) + 1;
}
/*
--
1.9.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: serial: 8250_mtk: Fix quot calculation
2014-10-09 16:23 [PATCH] tty: serial: 8250_mtk: Fix quot calculation Matthias Brugger
@ 2014-10-09 21:52 ` Greg KH
2014-10-10 8:10 ` Matthias Brugger
0 siblings, 1 reply; 5+ messages in thread
From: Greg KH @ 2014-10-09 21:52 UTC (permalink / raw)
To: Matthias Brugger
Cc: linux-kernel, jslaby, heiko, yingjoe.chen, ibanezchen,
linux-serial
On Thu, Oct 09, 2014 at 06:23:31PM +0200, Matthias Brugger wrote:
> The calculation of value quot for highspeed register set to three
> was wrong. This patch fixes the calculation so that the serial port
> for baudrates bigger then 576000 baud is working correctly.
>
> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> ---
> drivers/tty/serial/8250/8250_mtk.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index 1c4b4bf..4376c48 100644
> --- a/drivers/tty/serial/8250/8250_mtk.c
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
> /* Set to highest baudrate supported */
> if (baud >= 1152000)
> baud = 921600;
> - quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
> + quot = (port->uartclk / (256 * baud)) + 1;
> }
>
> /*
Has this always been incorrect, or was it caused by a specific patch?
Should it go to the stable kernels? If so, how far back?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: serial: 8250_mtk: Fix quot calculation
2014-10-09 21:52 ` Greg KH
@ 2014-10-10 8:10 ` Matthias Brugger
2014-10-20 11:30 ` Matthias Brugger
2014-11-06 3:27 ` Greg KH
0 siblings, 2 replies; 5+ messages in thread
From: Matthias Brugger @ 2014-10-10 8:10 UTC (permalink / raw)
To: Greg KH
Cc: linux-kernel@vger.kernel.org, jslaby, Heiko Stübner,
Yingjoe Chen, Howard Chen, linux-serial
2014-10-09 23:52 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
> On Thu, Oct 09, 2014 at 06:23:31PM +0200, Matthias Brugger wrote:
>> The calculation of value quot for highspeed register set to three
>> was wrong. This patch fixes the calculation so that the serial port
>> for baudrates bigger then 576000 baud is working correctly.
>>
>> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
>> ---
>> drivers/tty/serial/8250/8250_mtk.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
>> index 1c4b4bf..4376c48 100644
>> --- a/drivers/tty/serial/8250/8250_mtk.c
>> +++ b/drivers/tty/serial/8250/8250_mtk.c
>> @@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
>> /* Set to highest baudrate supported */
>> if (baud >= 1152000)
>> baud = 921600;
>> - quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
>> + quot = (port->uartclk / (256 * baud)) + 1;
>> }
>>
>> /*
>
> Has this always been incorrect, or was it caused by a specific patch?
It has always been incorrect :o
> Should it go to the stable kernels? If so, how far back?
No need to go to the stable kernels. The driver is only in linux-next.
Cheers,
Matthias Brugger
>
> thanks,
>
> greg k-h
--
motzblog.wordpress.com
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: serial: 8250_mtk: Fix quot calculation
2014-10-10 8:10 ` Matthias Brugger
@ 2014-10-20 11:30 ` Matthias Brugger
2014-11-06 3:27 ` Greg KH
1 sibling, 0 replies; 5+ messages in thread
From: Matthias Brugger @ 2014-10-20 11:30 UTC (permalink / raw)
To: Greg KH
Cc: linux-kernel@vger.kernel.org, jslaby, Heiko Stübner,
Yingjoe Chen, Howard Chen, linux-serial
Hi Greg,
2014-10-10 10:10 GMT+02:00 Matthias Brugger <matthias.bgg@gmail.com>:
> 2014-10-09 23:52 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
>> On Thu, Oct 09, 2014 at 06:23:31PM +0200, Matthias Brugger wrote:
>>> The calculation of value quot for highspeed register set to three
>>> was wrong. This patch fixes the calculation so that the serial port
>>> for baudrates bigger then 576000 baud is working correctly.
>>>
>>> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
>>> ---
>>> drivers/tty/serial/8250/8250_mtk.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
>>> index 1c4b4bf..4376c48 100644
>>> --- a/drivers/tty/serial/8250/8250_mtk.c
>>> +++ b/drivers/tty/serial/8250/8250_mtk.c
>>> @@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
>>> /* Set to highest baudrate supported */
>>> if (baud >= 1152000)
>>> baud = 921600;
>>> - quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
>>> + quot = (port->uartclk / (256 * baud)) + 1;
>>> }
>>>
>>> /*
>>
>> Has this always been incorrect, or was it caused by a specific patch?
>
> It has always been incorrect :o
>
>> Should it go to the stable kernels? If so, how far back?
>
> No need to go to the stable kernels. The driver is only in linux-next.
Any comments on that?
Thanks,
Matthias
>
> Cheers,
> Matthias Brugger
>
>>
>> thanks,
>>
>> greg k-h
>
>
>
> --
> motzblog.wordpress.com
--
motzblog.wordpress.com
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: serial: 8250_mtk: Fix quot calculation
2014-10-10 8:10 ` Matthias Brugger
2014-10-20 11:30 ` Matthias Brugger
@ 2014-11-06 3:27 ` Greg KH
1 sibling, 0 replies; 5+ messages in thread
From: Greg KH @ 2014-11-06 3:27 UTC (permalink / raw)
To: Matthias Brugger
Cc: linux-kernel@vger.kernel.org, jslaby, Heiko Stübner,
Yingjoe Chen, Howard Chen, linux-serial
On Fri, Oct 10, 2014 at 10:10:45AM +0200, Matthias Brugger wrote:
> 2014-10-09 23:52 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
> > On Thu, Oct 09, 2014 at 06:23:31PM +0200, Matthias Brugger wrote:
> >> The calculation of value quot for highspeed register set to three
> >> was wrong. This patch fixes the calculation so that the serial port
> >> for baudrates bigger then 576000 baud is working correctly.
> >>
> >> Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
> >> ---
> >> drivers/tty/serial/8250/8250_mtk.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> >> index 1c4b4bf..4376c48 100644
> >> --- a/drivers/tty/serial/8250/8250_mtk.c
> >> +++ b/drivers/tty/serial/8250/8250_mtk.c
> >> @@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
> >> /* Set to highest baudrate supported */
> >> if (baud >= 1152000)
> >> baud = 921600;
> >> - quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
> >> + quot = (port->uartclk / (256 * baud)) + 1;
> >> }
> >>
> >> /*
> >
> > Has this always been incorrect, or was it caused by a specific patch?
>
> It has always been incorrect :o
>
> > Should it go to the stable kernels? If so, how far back?
>
> No need to go to the stable kernels. The driver is only in linux-next.
Well, it's in 3.18-rc1, so it should at least go into 3.18-final. I'll
queue it up for that.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
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2014-10-09 16:23 [PATCH] tty: serial: 8250_mtk: Fix quot calculation Matthias Brugger
2014-10-09 21:52 ` Greg KH
2014-10-10 8:10 ` Matthias Brugger
2014-10-20 11:30 ` Matthias Brugger
2014-11-06 3:27 ` Greg KH
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