| Message ID | 1426429742-3041-1-git-send-email-ykaneko0929@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
On 3/15/2015 5:29 PM, Yoshihiro Kaneko wrote: > From: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com> > The current calculation method in the case of 9600bps, rounding error occurs > has become setting that occur timeout faster than the required time. When we > use 9600bps, 32byte buffer, 10 bit (CS8) and 100 HZ, it becomes 3 jiffies > (30msec). In fact it is necessary 33msec. This updates to the calculation > that are not actually less than the value set by the rounding error. > Also, this is nothing will be calculated value when there is no load. If there > are a lot of case load, overrun error will occur immediately. > This is by the buffer size to be calculated twice the DMA buffer, and add the > change of setting a sufficient time-out value. > Signedroff-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com> > Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com> > --- > This patch is based on the tty-next branch of Greg Kroah-Hartman's tty > tree. > drivers/tty/serial/sh-sci.c | 38 ++++++++++++++++++++++++++++++-------- > 1 file changed, 30 insertions(+), 8 deletions(-) > diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c > index 5b50c79..891116c 100644 > --- a/drivers/tty/serial/sh-sci.c > +++ b/drivers/tty/serial/sh-sci.c > @@ -1967,18 +1967,40 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, [...] > if (s->chan_rx) { > - s->rx_timeout = (port->timeout - HZ / 50) * s->buf_len_rx * 3 / > - port->fifosize / 2; > + unsigned int bits; > + > + /* byte size and parity */ > + switch (termios->c_cflag & CSIZE) { > + case CS5: *case* should at the same indentation level as *switch*. I guess you haven't run the patch thru scripts/checkpatch.pl? > + bits = 7; > + break; > + case CS6: > + bits = 8; > + break; > + case CS7: > + bits = 9; > + break; > + default: > + bits = 10; > + break; > + } [...] WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello, 2015-03-16 0:30 GMT+09:00 Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>: > On 3/15/2015 5:29 PM, Yoshihiro Kaneko wrote: > >> From: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com> > > >> The current calculation method in the case of 9600bps, rounding error >> occurs >> has become setting that occur timeout faster than the required time. When >> we >> use 9600bps, 32byte buffer, 10 bit (CS8) and 100 HZ, it becomes 3 jiffies >> (30msec). In fact it is necessary 33msec. This updates to the calculation >> that are not actually less than the value set by the rounding error. >> Also, this is nothing will be calculated value when there is no load. If >> there >> are a lot of case load, overrun error will occur immediately. >> This is by the buffer size to be calculated twice the DMA buffer, and add >> the >> change of setting a sufficient time-out value. > > >> Signedroff-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com> >> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com> >> --- > > >> This patch is based on the tty-next branch of Greg Kroah-Hartman's tty >> tree. > > >> drivers/tty/serial/sh-sci.c | 38 ++++++++++++++++++++++++++++++-------- >> 1 file changed, 30 insertions(+), 8 deletions(-) > > >> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c >> index 5b50c79..891116c 100644 >> --- a/drivers/tty/serial/sh-sci.c >> +++ b/drivers/tty/serial/sh-sci.c >> @@ -1967,18 +1967,40 @@ static void sci_set_termios(struct uart_port >> *port, struct ktermios *termios, > > [...] >> >> if (s->chan_rx) { >> - s->rx_timeout = (port->timeout - HZ / 50) * s->buf_len_rx >> * 3 / >> - port->fifosize / 2; >> + unsigned int bits; >> + >> + /* byte size and parity */ >> + switch (termios->c_cflag & CSIZE) { >> + case CS5: > > > *case* should at the same indentation level as *switch*. I guess you > haven't run the patch thru scripts/checkpatch.pl? Sorry, I forgot to run the script. Thanks, Kaneko > >> + bits = 7; >> + break; >> + case CS6: >> + bits = 8; >> + break; >> + case CS7: >> + bits = 9; >> + break; >> + default: >> + bits = 10; >> + break; >> + } > > [...] > > WBR, Sergei > -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index 5b50c79..891116c 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1967,18 +1967,40 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, #ifdef CONFIG_SERIAL_SH_SCI_DMA /* - * Calculate delay for 1.5 DMA buffers: see - * drivers/serial/serial_core.c::uart_update_timeout(). With 10 bits + * Calculate delay for 2 DMA buffers (4 FIFO). + * See drivers/serial/serial_core.c::uart_update_timeout(). With 10 bits * (CS8), 250Hz, 115200 baud and 64 bytes FIFO, the above function * calculates 1 jiffie for the data plus 5 jiffies for the "slop(e)." - * Then below we calculate 3 jiffies (12ms) for 1.5 DMA buffers (3 FIFO - * sizes), but it has been found out experimentally, that this is not - * enough: the driver too often needlessly runs on a DMA timeout. 20ms - * as a minimum seem to work perfectly. + * Then below we calculate 5 jiffies (20ms) for 2 DMA buffers (4 FIFO + * sizes), but when performing a faster transfer, value obtained by this + * formula is may not enough. Therefore, if value is smaller than 20msec, + * this sets 20msec as timeout of DMA. */ if (s->chan_rx) { - s->rx_timeout = (port->timeout - HZ / 50) * s->buf_len_rx * 3 / - port->fifosize / 2; + unsigned int bits; + + /* byte size and parity */ + switch (termios->c_cflag & CSIZE) { + case CS5: + bits = 7; + break; + case CS6: + bits = 8; + break; + case CS7: + bits = 9; + break; + default: + bits = 10; + break; + } + + if (termios->c_cflag & CSTOPB) + bits++; + if (termios->c_cflag & PARENB) + bits++; + s->rx_timeout = DIV_ROUND_UP((s->buf_len_rx * 2 * bits * HZ) / + (baud / 10), 10); dev_dbg(port->dev, "DMA Rx t-out %ums, tty t-out %u jiffies\n", s->rx_timeout * 1000 / HZ, port->timeout); if (s->rx_timeout < msecs_to_jiffies(20))