[PATCH v2] staging: greybus: loopback: Use fsleep() for delay

[pavankumaryalagada@gmail.com]

From: Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>

In the loopback function, usleep_range() is used for short delays
and msleep() for longer delays. This requires choosing the delay
function based on the requested time and converting microseconds
to milliseconds when using msleep().

Replace both functions with fsleep(), which chooses a delay
delay method based on the requested time. For short delays,
fsleep() allows up to 25% extra time instead of the fixed 100
microseconds. For longer delays, the old code rounds the
requested time down to whole milliseconds, while fsleep() rounds
it up when using msleep().

These changes may affect time between loopback operations and
the reported performance.

Suggested-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>
---
v2:
- Add more details about how fsleep() affects delays.
- Update the subject to include the loopback module.

v1: https://lore.kernel.org/outreachy/c482704b-903e-413d-ba7b-5bf31c0a6104@riscstar.com/T/#t
---
 drivers/staging/greybus/loopback.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index efc69c10cffe..2fe845eaef29 100644
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -898,12 +898,8 @@ static int gb_loopback_fn(void *data)
 		gb->send_count++;
 		mutex_unlock(&gb->mutex);
 
-		if (us_wait) {
-			if (us_wait < 20000)
-				usleep_range(us_wait, us_wait + 100);
-			else
-				msleep(us_wait / 1000);
-		}
+		if (us_wait)
+			fsleep(us_wait);
 	}
 
 	gb_pm_runtime_put_autosuspend(bundle);
-- 
2.43.0