From: Sean Young <sean@mess.org>
Date: Sat, 2 May 2020 12:50:52 +0000 (+0200)
Subject: media: gpio-ir-tx: improve precision of transmitted signal due to scheduling
X-Git-Tag: v5.10.7~2096^2~302
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ea8912b788f8144e7d32ee61e5ccba45424bef83;p=platform%2Fkernel%2Flinux-rpi.git

media: gpio-ir-tx: improve precision of transmitted signal due to scheduling

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@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---

diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c
index 18ca12d..6670398 100644
--- a/drivers/media/rc/gpio-ir-tx.c
+++ b/drivers/media/rc/gpio-ir-tx.c
@@ -79,13 +79,8 @@ 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]);