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From: Sean Young <sean@mess.org>
To: linux-media@vger.kernel.org
Subject: [PATCH 1/2] media: rc: improve precision of transmitted signal due to scheduling
Date: Wed,  6 May 2020 11:42:21 +0100	[thread overview]
Message-ID: <20200506104222.16188-1-sean@mess.org> (raw)

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 ndelay().

Signed-off-by: Sean Young <sean@mess.org>
---
 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 18ca12d78314c..66703989ae185 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]);
-- 
2.26.2


             reply	other threads:[~2020-05-06 10:42 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-06 10:42 Sean Young [this message]
2020-05-06 10:42 ` [PATCH 2/2] media: gpio-ir-tx: allow transmission without carrier Sean Young

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