Re: Re: [PATCH V3] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers
Hi Alan,
Thank you for your reply.
(2014/03/14 21:04), One Thousand Gnomes wrote:
@@ -2325,10 +2323,19 @@ serial8250_do_set_termios(struct uart_port *port,
struct ktermios *termios,
if ((baud < 2400 && !up->dma) || fifo_bug) {
fcr &= ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
+ /* Don't use user setting RX trigger */
+ up->fcr = 0;
This breaks
set fcr via sysfs
set baud rate below 2400
set baud rate higher
If baud < 2400 and the user has set a value then probably we should honour
OK, I'll add !up->fcr in this flow as follows:
/* NOTE: If fifo_bug is not set, a user can set RX trigger. */
if ((baud < 2400 && !up->dma && !up->fcr) || fifo_bug) {
fcr &= ~UART_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
up->fcr = 0;
}
it. If fifo_bug is set then we should never honour it (and should perhaps
eventually error it in the sysfs set).
When fifo_bug is set to "1", we need to check not only
whether (up->bugs & UART_BUG_PARITY) but whether parity is enabled.
We can check whether parity is enable only in this function currently,
so I think we need to store fifo_bug's value into up->fifo_bug and
refer it in the sysfs set(do_set_rx_int_trig()) as follows:
@do_set_rx_int_trig()
if (!(up->capabilities & UART_CAP_FIFO) || uport->fifosize <= 1
|| (up->fifo_bug & UART_BUG_PARITY))
return -EINVAL;
+static unsigned char convert_fcr2val(struct uart_8250_port *up,
+unsigned char fcr)
+{
+ unsigned char val = 0, trig_raw = fcr & UART_FCR_TRIGGER_MASK;
+
+ switch (up->port.type) {
+ case PORT_16550A:
+ if (trig_raw == UART_FCR_R_TRIG_00)
+ val = 1;
+ else if (trig_raw == UART_FCR_R_TRIG_01)
+ val = 4;
+ else if (trig_raw == UART_FCR_R_TRIG_10)
+ val = 8;
+ else if (trig_raw == UART_FCR_R_TRIG_11)
+ val = 14;
+ break;
Surely the default case should be returning 1 not 0 ?
In the default case, it returns "0" meaning error because "1" has
other meaning (1 byte RX trigger). But, "0" is not instinctive value for
the error, so it should return -EOPNOTSUPP here.
+static int convert_val2rxtrig(struct uart_8250_port *up, unsigned char val)
+{
+ switch (up->port.type) {
+ case PORT_16550A:
+ if (val == 1)
+ return UART_FCR_R_TRIG_00;
+ else if (val == 4)
+ return UART_FCR_R_TRIG_01;
+ else if (val == 8)
+ return UART_FCR_R_TRIG_10;
+ else if (val == 14)
+ return UART_FCR_R_TRIG_11;
What happens if you specify a meaningless value. Doing exact matching
means that you have to know the hardware exactly. How about
if (val < 4)
return UART_FCR_R_TRIG_00;
else if (val < 8)
return UART_FCR_R_TRIG_01;
else if (val < 14)
return UART_FCR_R_TRIG_10;
else
return UART_FCR_R_TRIG_11;
so you get the nearest lower value that the hardware can provide ?
It is a good idea. I was concerned about the same thing which users
must know the HW exactly.
I'll implement it as you say.
+ break;
+ default:
+ pr_info("Not support RX-trigger setting for this serial %u\n",
+ up->port.type);
That lets users spew into the logs. I think actually you just want
default:
return -EOPNOTSUPP;
OK, I'll use this.
Thank you,
Yoshihiro YUNOMAE
--
Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae...@hitachi.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: Re: [PATCH V3] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers
Hi Alan,
Thank you for your reply.
(2014/03/14 21:04), One Thousand Gnomes wrote:
@@ -2325,10 +2323,19 @@ serial8250_do_set_termios(struct uart_port *port,
struct ktermios *termios,
if ((baud 2400 !up-dma) || fifo_bug) {
fcr = ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
+ /* Don't use user setting RX trigger */
+ up-fcr = 0;
This breaks
set fcr via sysfs
set baud rate below 2400
set baud rate higher
If baud 2400 and the user has set a value then probably we should honour
OK, I'll add !up-fcr in this flow as follows:
/* NOTE: If fifo_bug is not set, a user can set RX trigger. */
if ((baud 2400 !up-dma !up-fcr) || fifo_bug) {
fcr = ~UART_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
up-fcr = 0;
}
it. If fifo_bug is set then we should never honour it (and should perhaps
eventually error it in the sysfs set).
When fifo_bug is set to 1, we need to check not only
whether (up-bugs UART_BUG_PARITY) but whether parity is enabled.
We can check whether parity is enable only in this function currently,
so I think we need to store fifo_bug's value into up-fifo_bug and
refer it in the sysfs set(do_set_rx_int_trig()) as follows:
@do_set_rx_int_trig()
if (!(up-capabilities UART_CAP_FIFO) || uport-fifosize = 1
|| (up-fifo_bug UART_BUG_PARITY))
return -EINVAL;
+static unsigned char convert_fcr2val(struct uart_8250_port *up,
+unsigned char fcr)
+{
+ unsigned char val = 0, trig_raw = fcr UART_FCR_TRIGGER_MASK;
+
+ switch (up-port.type) {
+ case PORT_16550A:
+ if (trig_raw == UART_FCR_R_TRIG_00)
+ val = 1;
+ else if (trig_raw == UART_FCR_R_TRIG_01)
+ val = 4;
+ else if (trig_raw == UART_FCR_R_TRIG_10)
+ val = 8;
+ else if (trig_raw == UART_FCR_R_TRIG_11)
+ val = 14;
+ break;
Surely the default case should be returning 1 not 0 ?
In the default case, it returns 0 meaning error because 1 has
other meaning (1 byte RX trigger). But, 0 is not instinctive value for
the error, so it should return -EOPNOTSUPP here.
+static int convert_val2rxtrig(struct uart_8250_port *up, unsigned char val)
+{
+ switch (up-port.type) {
+ case PORT_16550A:
+ if (val == 1)
+ return UART_FCR_R_TRIG_00;
+ else if (val == 4)
+ return UART_FCR_R_TRIG_01;
+ else if (val == 8)
+ return UART_FCR_R_TRIG_10;
+ else if (val == 14)
+ return UART_FCR_R_TRIG_11;
What happens if you specify a meaningless value. Doing exact matching
means that you have to know the hardware exactly. How about
if (val 4)
return UART_FCR_R_TRIG_00;
else if (val 8)
return UART_FCR_R_TRIG_01;
else if (val 14)
return UART_FCR_R_TRIG_10;
else
return UART_FCR_R_TRIG_11;
so you get the nearest lower value that the hardware can provide ?
It is a good idea. I was concerned about the same thing which users
must know the HW exactly.
I'll implement it as you say.
+ break;
+ default:
+ pr_info(Not support RX-trigger setting for this serial %u\n,
+ up-port.type);
That lets users spew into the logs. I think actually you just want
default:
return -EOPNOTSUPP;
OK, I'll use this.
Thank you,
Yoshihiro YUNOMAE
--
Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae...@hitachi.com
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: Re: [PATCH V3] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers
Hi Heikki,
Thank you for your reply.
(2014/03/14 23:16), Heikki Krogerus wrote:
Hi,
On Fri, Mar 14, 2014 at 11:21:54AM +0900, Yoshihiro YUNOMAE wrote:
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
{
- unsigned char fcr;
-
serial8250_clear_fifos(p);
- fcr = uart_config[p->port.type].fcr;
- serial_out(p, UART_FCR, fcr);
+ p->fcr = uart_config[p->port.type].fcr;
+ serial_out(p, UART_FCR, p->fcr);
You should allow also the probe drivers to set this..
if (!p->fcr)
p->fcr = uart_config[p->port.type].fcr;
Oh, I'll fix it.
}
EXPORT_SYMBOL_GPL(serial8250_clear_and_reinit_fifos);
@@ -2325,10 +2323,19 @@ serial8250_do_set_termios(struct uart_port *port,
struct ktermios *termios,
if ((baud < 2400 && !up->dma) || fifo_bug) {
fcr &= ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
+ /* Don't use user setting RX trigger */
+ up->fcr = 0;
I don't know about this but..
}
}
/*
+* If up->fcr exists, a user has opened this port, changed RX trigger,
+* or read RX trigger before. So, we don't need to change up->fcr here.
+*/
+ if (!up->fcr)
+ up->fcr = fcr;
Why not just set fcr = up->fcr in the beginning of the function?
Ah, we don't need to set up->fcr = 0 in the previous flow when we
implement as follows:
unsigned char fcr = up->fcr;
... ...
/*
* If fcr exists, a user has opened this port, changed RX
* trigger, or read RX trigger before. If so, we do not change
* fcr.
*/
if (!fcr)
fcr = uart_config[port_type].fcr;
if ((baud < 2400 && !up->dma) || fifo_bug) {
fcr &= ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
}
up->fcr = fcr;
+static int do_set_rx_int_trig(struct tty_port *port, unsigned char val)
+{
+ struct uart_state *state = container_of(port, struct uart_state, port);
+ struct uart_port *uport = state->uart_port;
+ struct uart_8250_port *up =
+ container_of(uport, struct uart_8250_port, port);
+ unsigned char fcr;
+ int rx_trig;
+
+ if (!(up->capabilities & UART_CAP_FIFO) || uport->fifosize <= 1)
+ return -EINVAL;
+
+ rx_trig = convert_val2rxtrig(up, val);
+ if (rx_trig < 0)
+ return rx_trig;
+
+ serial8250_clear_fifos(up);
+ if (!up->fcr)
+ /* termios is not set yet */
+ fcr = uart_config[up->port.type].fcr;
+ else
+ fcr = up->fcr;
+ fcr &= ~UART_FCR_TRIGGER_MASK;
+ fcr |= (unsigned char)rx_trig;
+ up->fcr = fcr;
+ serial_out(up, UART_FCR, up->fcr);
+ return 0;
+}
Where are you setting UART_FCR_ENABLE_FIFO bit? Am I missing
something?
In these implementation, the driver sets up->fcr as
uart_config[up->port.type].fcr first and changes only RX trigger. So,
we don't need to set the bit in a direct way.
Thank you,
Yoshihiro YUNOMAE
--
Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae...@hitachi.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: Re: [PATCH V3] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers
Hi Heikki,
Thank you for your reply.
(2014/03/14 23:16), Heikki Krogerus wrote:
Hi,
On Fri, Mar 14, 2014 at 11:21:54AM +0900, Yoshihiro YUNOMAE wrote:
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
{
- unsigned char fcr;
-
serial8250_clear_fifos(p);
- fcr = uart_config[p-port.type].fcr;
- serial_out(p, UART_FCR, fcr);
+ p-fcr = uart_config[p-port.type].fcr;
+ serial_out(p, UART_FCR, p-fcr);
You should allow also the probe drivers to set this..
if (!p-fcr)
p-fcr = uart_config[p-port.type].fcr;
Oh, I'll fix it.
}
EXPORT_SYMBOL_GPL(serial8250_clear_and_reinit_fifos);
@@ -2325,10 +2323,19 @@ serial8250_do_set_termios(struct uart_port *port,
struct ktermios *termios,
if ((baud 2400 !up-dma) || fifo_bug) {
fcr = ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
+ /* Don't use user setting RX trigger */
+ up-fcr = 0;
I don't know about this but..
}
}
/*
+* If up-fcr exists, a user has opened this port, changed RX trigger,
+* or read RX trigger before. So, we don't need to change up-fcr here.
+*/
+ if (!up-fcr)
+ up-fcr = fcr;
Why not just set fcr = up-fcr in the beginning of the function?
Ah, we don't need to set up-fcr = 0 in the previous flow when we
implement as follows:
unsigned char fcr = up-fcr;
... snip ...
/*
* If fcr exists, a user has opened this port, changed RX
* trigger, or read RX trigger before. If so, we do not change
* fcr.
*/
if (!fcr)
fcr = uart_config[port_type].fcr;
if ((baud 2400 !up-dma) || fifo_bug) {
fcr = ~UART_FCR_TRIGGER_MASK;
fcr |= UART_FCR_TRIGGER_1;
}
up-fcr = fcr;
snip
+static int do_set_rx_int_trig(struct tty_port *port, unsigned char val)
+{
+ struct uart_state *state = container_of(port, struct uart_state, port);
+ struct uart_port *uport = state-uart_port;
+ struct uart_8250_port *up =
+ container_of(uport, struct uart_8250_port, port);
+ unsigned char fcr;
+ int rx_trig;
+
+ if (!(up-capabilities UART_CAP_FIFO) || uport-fifosize = 1)
+ return -EINVAL;
+
+ rx_trig = convert_val2rxtrig(up, val);
+ if (rx_trig 0)
+ return rx_trig;
+
+ serial8250_clear_fifos(up);
+ if (!up-fcr)
+ /* termios is not set yet */
+ fcr = uart_config[up-port.type].fcr;
+ else
+ fcr = up-fcr;
+ fcr = ~UART_FCR_TRIGGER_MASK;
+ fcr |= (unsigned char)rx_trig;
+ up-fcr = fcr;
+ serial_out(up, UART_FCR, up-fcr);
+ return 0;
+}
Where are you setting UART_FCR_ENABLE_FIFO bit? Am I missing
something?
In these implementation, the driver sets up-fcr as
uart_config[up-port.type].fcr first and changes only RX trigger. So,
we don't need to set the bit in a direct way.
Thank you,
Yoshihiro YUNOMAE
--
Yoshihiro YUNOMAE
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: yoshihiro.yunomae...@hitachi.com
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
