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.ez@xxxxxxxxxxx
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