[U-Boot] [PATCH] common/xyzModem.c: Fix delay timeout calculation
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@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); counter++; } if (tstc ())
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@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); counter++;
Reviewed-by: Stefan Roese sr@denx.de
Thanks, Stefan
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@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@denx.de
Thanks, Stefan
Hi Andrew,
On 26.08.2016 15:40, Andrew F. Davis wrote:
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@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++;
Yes, this should also work and is a less intrusive change. But the result is that the delay is at least 20ms each time. And the original version had a much smaller delay here.
Even better would be if you change the loop to a timer based timeout detection. Please grep for get_timer() to see some examples.
Thanks, Stefan
On 08/26/2016 08:43 AM, Stefan Roese wrote:
Hi Andrew,
On 26.08.2016 15:40, Andrew F. Davis wrote:
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@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++;Yes, this should also work and is a less intrusive change. But the result is that the delay is at least 20ms each time. And the original version had a much smaller delay here.
Even better would be if you change the loop to a timer based timeout detection. Please grep for get_timer() to see some examples.
I think that will require more work then needed right now, at some point a lot of the xyzModem stuff will need cleaned/re-written, for now this is a working fix for something that is broken, so I'll re-submit v2 with the above change.
Thanks, Stefan
participants (2)
-
Andrew F. Davis -
Stefan Roese