OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

TTY: hvc_dcc: probe for a JTAG connection before registering 

Enabling the ARM DCC console and using without a JTAG connection will
simply hang the system. Since distros like to turn on all options, this
is a reoccurring problem to debug. We can do better by checking if
anything is attached and handling characters. There is no way to probe
this, so send a newline and check that it is handled.

Cc: Paolo Pisati <paolo.pisati@canonical.com>
Cc: Tim Gardner <tim.gardner@canonical.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rob Herring 2013-09-24 21:05:58 -05:00 committed by Greg Kroah-Hartman
parent 469d6d0631
commit f377775dc0
1 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/tty/hvc/hvc_dcc.c
View File

@ -86,6 +86,21 @@ static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
return i;
}
static bool hvc_dcc_check(void)
{
unsigned long time = jiffies + (HZ / 10);
/* Write a test character to check if it is handled */
__dcc_putchar('\n');
while (time_is_after_jiffies(time)) {
if (!(__dcc_getstatus() & DCC_STATUS_TX))
return true;
}
return false;
}
static const struct hv_ops hvc_dcc_get_put_ops = {
.get_chars = hvc_dcc_get_chars,
.put_chars = hvc_dcc_put_chars,
@ -93,6 +108,9 @@ static const struct hv_ops hvc_dcc_get_put_ops = {
static int __init hvc_dcc_console_init(void)
{
if (!hvc_dcc_check())
return -ENODEV;
hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
return 0;
}
@ -100,6 +118,9 @@ console_initcall(hvc_dcc_console_init);
static int __init hvc_dcc_init(void)
{
if (!hvc_dcc_check())
return -ENODEV;
hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
return 0;
}