xyz-modem: Change getc timeout loop waiting

This fixes the loop delay when using a hw watchdog. In case a watchdog is used that accesses CPU registers, the defined delay of 20us in a tight loop will cause a huge delay in the actual timeout seen. This is caused by the fact that udelay will inheritantly call WATCHDOG_RESET. Together with the omap wdt implementation, the seen timeout increases up to around 30s. This makes the loop very slow and causes long delays when using the modem. Instead, implement the 2 sec loop by using the timer interface to know when to break out of the timeout loop. Watchdog kicking is taken care of by getc(). Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>

xyz-modem: Change getc timeout loop waiting
This fixes the loop delay when using a hw watchdog. In case a watchdog is used that accesses CPU registers, the defined delay of 20us in a tight loop will cause a huge delay in the actual timeout seen. This is caused by the fact that udelay will inheritantly call WATCHDOG_RESET. Together with the omap wdt implementation, the seen timeout increases up to around 30s. This makes the loop very slow and causes long delays when using the modem. Instead, implement the 2 sec loop by using the timer interface to know when to break out of the timeout loop. Watchdog kicking is taken care of by getc(). Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
tomas.melin@vaisala.com · Tom Rini · Eric Lee · Eric Lee · Eric Lee · Eric Lee
1 parent aa6ab905b2
Showing 1 changed file with 5 additions and 5 deletions Side-by-side Diff
common/xyzModem.c
@@ -71,12 +71,12 @@
 static int
 CYGACC_COMM_IF_GETC_TIMEOUT (char chan, char *c)
 {
-#define DELAY 20
-  unsigned long counter = 0;
-  while (!tstc () && (counter < xyzModem_CHAR_TIMEOUT * 1000 / DELAY))
+
+  ulong now = get_timer(0);
+  while (!tstc ())
     {
-      udelay (DELAY);
-      counter++;
+      if (get_timer(now) > xyzModem_CHAR_TIMEOUT)
+        break;
     }
   if (tstc ())
     {
...	...	@@ -71,12 +71,12 @@
71	71	static int
72	72	CYGACC_COMM_IF_GETC_TIMEOUT (char chan, char *c)
73	73	{
74		-#define DELAY 20
75		- unsigned long counter = 0;
76		- while (!tstc () && (counter < xyzModem_CHAR_TIMEOUT * 1000 / DELAY))
	74	+
	75	+ ulong now = get_timer(0);
	76	+ while (!tstc ())
77	77	{
78		- udelay (DELAY);
79		- counter++;
	78	+ if (get_timer(now) > xyzModem_CHAR_TIMEOUT)
	79	+ break;
80	80	}
81	81	if (tstc ())
82	82	{