[PATCH 4.14 42/91] media: gpio-ir-tx: improve precision of transmitted signal due to scheduling

[Greg Kroah-Hartman]

From: Sean Young <sean@xxxxxxxx>

[ Upstream commit ea8912b788f8144e7d32ee61e5ccba45424bef83 ]

usleep_range() may take longer than the max argument due to scheduling,
especially under load. This is causing random errors in the transmitted
IR. Remove the usleep_range() in favour of busy-looping with udelay().

Signed-off-by: Sean Young <sean@xxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/media/rc/gpio-ir-tx.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c
index cd476cab97820..4e70b67ccd181 100644
--- a/drivers/media/rc/gpio-ir-tx.c
+++ b/drivers/media/rc/gpio-ir-tx.c
@@ -87,13 +87,8 @@ static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
 			// space
 			edge = ktime_add_us(edge, txbuf[i]);
 			delta = ktime_us_delta(edge, ktime_get());
-			if (delta > 10) {
-				spin_unlock_irqrestore(&gpio_ir->lock, flags);
-				usleep_range(delta, delta + 10);
-				spin_lock_irqsave(&gpio_ir->lock, flags);
-			} else if (delta > 0) {
+			if (delta > 0)
 				udelay(delta);
-			}
 		} else {
 			// pulse
 			ktime_t last = ktime_add_us(edge, txbuf[i]);
-- 
2.25.1