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

[ 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@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Sean Young 2020-05-02 14:50:52 +02:00 committed by Greg Kroah-Hartman
parent 6ba04701b8
commit 8f409e764c
1 changed files with 1 additions and 6 deletions
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7
drivers/media/rc/gpio-ir-tx.c
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@ -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]);