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authorSean Young <sean@mess.org>2020-08-13 11:08:49 +0200
committerMauro Carvalho Chehab <mchehab+huawei@kernel.org>2020-08-28 14:06:36 +0200
commit1451b93223bbe3b4e9c91fca6b451d00667c5bf0 (patch)
tree06315fe98be8afb94797cdf14511086da86d2bbc
parenta2e2d73fa28136598e84db9d021091f1b98cbb1a (diff)
media: gpio-ir-tx: spinlock is not needed to disable interrupts
During bit-banging the IR on a gpio pin, we cannot be scheduled or have anything interrupt us, else the generated signal will be incorrect. Therefore, we need to disable interrupts on the local cpu. This also disables preemption. local_irq_disable() does exactly what we need and does not require a spinlock. Signed-off-by: Sean Young <sean@mess.org> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
-rw-r--r--drivers/media/rc/gpio-ir-tx.c16
1 files changed, 5 insertions, 11 deletions
diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c
index f33b443bfa47..c6cd2e6d8e65 100644
--- a/drivers/media/rc/gpio-ir-tx.c
+++ b/drivers/media/rc/gpio-ir-tx.c
@@ -19,8 +19,6 @@ struct gpio_ir {
struct gpio_desc *gpio;
unsigned int carrier;
unsigned int duty_cycle;
- /* we need a spinlock to hold the cpu while transmitting */
- spinlock_t lock;
};
static const struct of_device_id gpio_ir_tx_of_match[] = {
@@ -53,12 +51,11 @@ static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
- unsigned long flags;
ktime_t edge;
s32 delta;
int i;
- spin_lock_irqsave(&gpio_ir->lock, flags);
+ local_irq_disable();
edge = ktime_get();
@@ -72,14 +69,11 @@ static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
}
gpiod_set_value(gpio_ir->gpio, 0);
-
- spin_unlock_irqrestore(&gpio_ir->lock, flags);
}
static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
uint count)
{
- unsigned long flags;
ktime_t edge;
/*
* delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
@@ -95,7 +89,7 @@ static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
(NSEC_PER_SEC / 100), gpio_ir->carrier);
- spin_lock_irqsave(&gpio_ir->lock, flags);
+ local_irq_disable();
edge = ktime_get();
@@ -128,19 +122,20 @@ static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
edge = last;
}
}
-
- spin_unlock_irqrestore(&gpio_ir->lock, flags);
}
static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
unsigned int count)
{
struct gpio_ir *gpio_ir = dev->priv;
+ unsigned long flags;
+ local_irq_save(flags);
if (gpio_ir->carrier)
gpio_ir_tx_modulated(gpio_ir, txbuf, count);
else
gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
+ local_irq_restore(flags);
return count;
}
@@ -176,7 +171,6 @@ static int gpio_ir_tx_probe(struct platform_device *pdev)
gpio_ir->carrier = 38000;
gpio_ir->duty_cycle = 50;
- spin_lock_init(&gpio_ir->lock);
rc = devm_rc_register_device(&pdev->dev, rcdev);
if (rc < 0)

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