[U-Boot] [PATCH] common/xyzModem.c: Fix delay timeout calculation

[Andrew F. Davis]

On 08/26/2016 12:18 AM, Stefan Roese wrote:
> On 25.08.2016 20:43, Andrew F. Davis wrote:
>> When waiting for input in CYGACC_COMM_IF_GETC_TIMEOUT we delay 2
>> seconds by incrementing and checking a counter variable every 20
>> uSeconds. The overhead in the loop calling tstc() millions of times
>> causes the timeout to be closer to 20 seconds. Delay longer per iteration
>> to reduce overhead and bring the timeout back closer to the correct time.
>>
>> Signed-off-by: Andrew F. Davis <afd at ti.com>
>> ---
>>  common/xyzModem.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/common/xyzModem.c b/common/xyzModem.c
>> index 5656aac..c3f2afc 100644
>> --- a/common/xyzModem.c
>> +++ b/common/xyzModem.c
>> @@ -71,11 +71,10 @@ typedef int cyg_int32;
>>  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))
>> +  while (!tstc () && (counter < xyzModem_CHAR_TIMEOUT))
>>      {
>> -      udelay (DELAY);
>> +      mdelay (1);

Thinking about this more, all we have to change is to remove the "*
1000" and switch to mdelay. That's a smaller change and results in an
even more correct timeout time.

 CYGACC_COMM_IF_GETC_TIMEOUT (char chan, char *c)
 {
 #define DELAY 20
 unsigned long counter = 0;
-  while (!tstc () && (counter < xyzModem_CHAR_TIMEOUT * 1000 / DELAY))
+  while (!tstc () && (counter < xyzModem_CHAR_TIMEOUT / DELAY))
   {
-      udelay (DELAY);
+      mdelay (DELAY);
       counter++;
   }

>>        counter++;
>>      }
>>    if (tstc ())
> 
> Reviewed-by: Stefan Roese <sr at denx.de>
> 
> Thanks,
> Stefan