lkml.org 
[lkml]   [2012]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRE: tty/serial: Need clarification on Support for 4+M Baudrate
Thanks, explicit termios(with flags) structure usage helped(log below), however, 
the dependent Bluetooth uart driver switches the uart baud rates
between 115K(during initialization), 9600(during low power) and
4+M(data tfr), in this juncture I need to handle termios structure switching
accordingly else I see c_cflags getting messed up effecting next baud switch change.

================================
[ 9.070648] alloc_set_baud_rate_cmd Setting arbitrary baudrate using BOTHER baudrate:89 c_cflag:020000016260
[ 9.164581] tty_termios_encode_baud_rate c_ispeed:4050000 c_ospeed:4050000 c_cflag:020000016260
[ 9.173278] tty_termios_encode_baud_rate checking precise weird baudrate c_cflag:020000006260 oclose:0 iclose:81000 ibinput:0
[ 9.187103] tty_termios_encode_baud_rate did we find close match? i:31 n_baud_table31 ifound:30 ofound:-1
[ 9.197570] tty_termios_encode_baud_rate BOTHER, c_cflag:022003616260
[ 9.214630] tty_termios_baud_rate:(Arb'ry baud set) c_cflag:022003616260 cbaud:010000
[ 9.222503] pl011_set_termios i_speed:4050000 o_speed:4050000
[ 9.231384] tty_termios_baud_rate:(Arb'ry baud set) c_cflag:022003616260 cbaud:010000
[ 9.246643] pl011_set_termios baud:4050000 uart_clk:38400000 port:0 IBRD:1 FBRD:12
[ 9.254730] XXXXXX-uart XXXXXX-uart.0: Baud rate changed to 4050000 baud
================================

Thanks,
Rajanikanth

> 4.05M Arbitrary Baud Setting Sequence:
> [ 9.664703] alloc_set_baud_rate_cmd Setting arbitrary baudrate using BOTHER baudrate:89 c_cflag:020000016262
> [ 9.774658] XXXXXX_hci_uart_set_baudrate c_cflag:020000016262 baud:4050000

4050000 seems a bit odd - you want cflag&CBAUD == BOTHER so I'd expect
the low bits to end rather different things to 6262 ?

So something like

struct ktermios new = *tty->termios;
new.c_cflag &= ~(CBAUD|CIBAUD);
new.c_cflag |= BOTHER;
new.c_ispeed = 4050000;
new.c_ospeed = 4050000;
tty_set_termios(tty, &new); /* Can sleep */

/* Returned new will now hold actual values selected */

should do the trick providing the low level driver supports the rate.

Alan


\
 
 \ /
  Last update: 2012-01-13 15:39    [W:0.030 / U:0.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site