Hi Matthias,
On Fri, Jul 21, 2017 at 04:12:45PM +0200, Matthias Reichl wrote:
> Hi Sean,
>
> On Fri, Jul 07, 2017 at 10:51:59AM +0100, Sean Young wrote:
> > This is a simple bit-banging GPIO IR TX driver.
>
> thanks a lot for the driver, this is highly appreciated!
>
> I tested the patch series on a RPi2, against RPi downstream kernel
> 4.13-rc1, and noticed an issue: the polarity of the gpio seems
> to be reversed.
>
> Other than the polarity issue the driver seems to work fine -
> at least on the scope screen. Didn't have an IR transmitter to
> do some real tests yet.
>
> I've configured the gpio as active high:
>
> gpio_ir_tx: gpio-ir-transmitter {
> compatible = "gpio-ir-tx";
> gpios = <&gpio 18 0>;
> };
>
> However, when loading the gpio-ir-tx driver the gpio pin changed
> to 3.3V. I did some tests with ir-ctl -S, idle state of the signal
> was 3.3V, active state 0V.
>
> I think it's better to use the descriptor based gpio functions
> instead of the legacy number based ones. That'll simplify the
> driver and it can delegate polarity handling to gpiod.
You're absolutely right, this is much nicer and makes the driver
shorter.
> Proposed changes and comments are inline. I've also included
> the patch against your patch that I've been testing with at the
> end of the message.
I agree with all your comments. However, we need a Signed-off-by:
line to use your patch, thank you.
Regards,
Sean
>
> > diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c
> > new file mode 100644
> > index 0000000..7a5371d
> > --- /dev/null
> > +++ b/drivers/media/rc/gpio-ir-tx.c
> > @@ -0,0 +1,189 @@
> > +/*
> > + * Copyright (C) 2017 Sean Young <s...@mess.org>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + */
> > +
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/gpio.h>
>
> use linux/gpio/consumer.h instead of linux/gpio.h
>
> > +#include <linux/delay.h>
> > +#include <linux/slab.h>
> > +#include <linux/of.h>
> > +#include <linux/of_gpio.h>
>
> of_gpio.h can be dropped
>
> > +#include <linux/platform_device.h>
> > +#include <media/rc-core.h>
> > +
> > +#define DRIVER_NAME "gpio-ir-tx"
> > +#define DEVICE_NAME "GPIO Bit Banging IR Transmitter"
> > +
> > +struct gpio_ir {
> > + int gpio_nr;
> > + bool active_low;
>
> Replace these 2 fields with
> 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[] = {
> > + { .compatible = "gpio-ir-tx", },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
> > +
> > +static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
> > +{
> > + struct gpio_ir *gpio_ir = dev->priv;
> > +
> > + gpio_ir->duty_cycle = duty_cycle;
> > +
> > + return 0;
> > +}
> > +
> > +static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
> > +{
> > + struct gpio_ir *gpio_ir = dev->priv;
> > +
> > + if (!carrier)
> > + return -EINVAL;
> > +
> > + gpio_ir->carrier = carrier;
> > +
> > + return 0;
> > +}
> > +
> > +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;
> > + ktime_t edge;
> > + /*
> > + * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
> > + * m68k ndelay(s64) does not compile; so use s32 rather than s64.
> > + */
> > + s32 delta;
> > + int i;
> > + unsigned int pulse, space;
> > +
> > + /* Ensure the dividend fits into 32 bit */
> > + pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
> > + gpio_ir->carrier);
> > + space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
> > + (NSEC_PER_SEC / 100), gpio_ir->carrier);
> > +
> > + spin_lock_irqsave(&gpio_ir->lock, flags);
> > +
> > + edge = ktime_get();
> > +
> > + for (i = 0; i < count; i++) {
> > + if (i % 2) {
> > + // 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) {
> > + udelay(delta);
> > + }
> > + } else {
> > + // pulse
> > + ktime_t last = ktime_add_us(edge, txbuf[i]);
> > +
> > + while (ktime_get() < last) {
> > + gpio_set_value(gpio_ir->gpio_nr,
> > + gpio_ir->active_low);
>
> gpiod_set_value(gpio_ir->gpio, 1);
>
> > + edge += pulse;
> > + delta = edge - ktime_get();
> > + if (delta > 0)
> > + ndelay(delta);
> > + gpio_set_value(gpio_ir->gpio_nr,
> > + !gpio_ir->active_low);
>
> gpiod_set_value(gpio_ir->gpio, 0);
>
> > + edge += space;
> > + delta = edge - ktime_get();
> > + if (delta > 0)
> > + ndelay(delta);
> > + }
> > +
> > + edge = last;
> > + }
> > + }
> > +
> > + spin_unlock_irqrestore(&gpio_ir->lock, flags);
> > +
> > + return count;
> > +}
> > +
> > +static int gpio_ir_tx_probe(struct platform_device *pdev)
> > +{
> > + struct gpio_ir *gpio_ir;
> > + struct rc_dev *rcdev;
> > + enum of_gpio_flags flags;
> > + int rc, gpio;
>
> Flags can be dropped, gpio as well.
>
> > +
> > + gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
> > + if (gpio < 0) {
> > + if (gpio != -EPROBE_DEFER)
> > + dev_err(&pdev->dev, "Failed to get gpio flags (%d)\n",
> > + gpio);
> > + return -EINVAL;
> > + }
>
> Drop this and move getting the gpio a bit down so we don't need
> a temp variable.
>
> > +
> > + gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
> > + if (!gpio_ir)
> > + return -ENOMEM;
> > +
> > + rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
> > + if (!rcdev)
> > + return -ENOMEM;
>
> get the gpio here, configure it to output with logical low (idle)
> level and store it in gpio_ir:
>
> gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
> if (IS_ERR(gpio_ir->gpio)) {
> if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
> dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
> PTR_ERR(gpio_ir->gpio));
> return PTR_ERR(gpio_ir->gpio);
> }
>
> > +
> > + rcdev->priv = gpio_ir;
> > + rcdev->driver_name = DRIVER_NAME;
> > + rcdev->device_name = DEVICE_NAME;
> > + rcdev->tx_ir = gpio_ir_tx;
> > + rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
> > + rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
> > +
> > + gpio_ir->gpio_nr = gpio;
> > + gpio_ir->active_low = (flags & OF_GPIO_ACTIVE_LOW) != 0;
>
> drop gpio_nr and active_low
>
> > + gpio_ir->carrier = 38000;
> > + gpio_ir->duty_cycle = 50;
> > + spin_lock_init(&gpio_ir->lock);
> > +
> > + rc = devm_gpio_request(&pdev->dev, gpio, "gpio-ir-tx");
> > + if (rc < 0)
> > + return rc;
> > +
> > + rc = gpio_direction_output(gpio, !gpio_ir->active_low);
> > + if (rc < 0)
> > + return rc;
>
> drop devm_gpio_request and gpio_direction_output, that is already
> handled by devm_gpiod_get.
>
> > +
> > + rc = devm_rc_register_device(&pdev->dev, rcdev);
> > + if (rc < 0)
> > + dev_err(&pdev->dev, "failed to register rc device\n");
> > +
> > + return rc;
> > +}
> > +
> > +static struct platform_driver gpio_ir_tx_driver = {
> > + .probe = gpio_ir_tx_probe,
> > + .driver = {
> > + .name = DRIVER_NAME,
> > + .of_match_table = of_match_ptr(gpio_ir_tx_of_match),
> > + },
> > +};
> > +module_platform_driver(gpio_ir_tx_driver);
> > +
> > +MODULE_DESCRIPTION("GPIO Bit Banging IR Transmitter");
> > +MODULE_AUTHOR("Sean Young <s...@mess.org>");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.9.4
I agree with your comments.
>
> so long,
>
> Hias
> ---
> diff --git a/drivers/media/rc/gpio-ir-tx.c b/drivers/media/rc/gpio-ir-tx.c
> index 7a5371dbb360..ca6834d09467 100644
> --- a/drivers/media/rc/gpio-ir-tx.c
> +++ b/drivers/media/rc/gpio-ir-tx.c
> @@ -13,11 +13,10 @@
>
> #include <linux/kernel.h>
> #include <linux/module.h>
> -#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/delay.h>
> #include <linux/slab.h>
> #include <linux/of.h>
> -#include <linux/of_gpio.h>
> #include <linux/platform_device.h>
> #include <media/rc-core.h>
>
> @@ -25,8 +24,7 @@
> #define DEVICE_NAME "GPIO Bit Banging IR Transmitter"
>
> struct gpio_ir {
> - int gpio_nr;
> - bool active_low;
> + struct gpio_desc *gpio;
> unsigned int carrier;
> unsigned int duty_cycle;
> /* we need a spinlock to hold the cpu while transmitting */
> @@ -101,14 +99,12 @@ static int gpio_ir_tx(struct rc_dev *dev, unsigned int
> *txbuf,
> ktime_t last = ktime_add_us(edge, txbuf[i]);
>
> while (ktime_get() < last) {
> - gpio_set_value(gpio_ir->gpio_nr,
> - gpio_ir->active_low);
> + gpiod_set_value(gpio_ir->gpio, 1);
> edge += pulse;
> delta = edge - ktime_get();
> if (delta > 0)
> ndelay(delta);
> - gpio_set_value(gpio_ir->gpio_nr,
> - !gpio_ir->active_low);
> + gpiod_set_value(gpio_ir->gpio, 0);
> edge += space;
> delta = edge - ktime_get();
> if (delta > 0)
> @@ -128,16 +124,7 @@ static int gpio_ir_tx_probe(struct platform_device *pdev)
> {
> struct gpio_ir *gpio_ir;
> struct rc_dev *rcdev;
> - enum of_gpio_flags flags;
> - int rc, gpio;
> -
> - gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
> - if (gpio < 0) {
> - if (gpio != -EPROBE_DEFER)
> - dev_err(&pdev->dev, "Failed to get gpio flags (%d)\n",
> - gpio);
> - return -EINVAL;
> - }
> + int rc;
>
> gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
> if (!gpio_ir)
> @@ -147,6 +134,14 @@ static int gpio_ir_tx_probe(struct platform_device *pdev)
> if (!rcdev)
> return -ENOMEM;
>
> + gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
> + if (IS_ERR(gpio_ir->gpio)) {
> + if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
> + dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
> + PTR_ERR(gpio_ir->gpio));
> + return PTR_ERR(gpio_ir->gpio);
> + }
> +
> rcdev->priv = gpio_ir;
> rcdev->driver_name = DRIVER_NAME;
> rcdev->device_name = DEVICE_NAME;
> @@ -154,20 +149,10 @@ static int gpio_ir_tx_probe(struct platform_device
> *pdev)
> rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
> rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
>
> - gpio_ir->gpio_nr = gpio;
> - gpio_ir->active_low = (flags & OF_GPIO_ACTIVE_LOW) != 0;
> gpio_ir->carrier = 38000;
> gpio_ir->duty_cycle = 50;
> spin_lock_init(&gpio_ir->lock);
>
> - rc = devm_gpio_request(&pdev->dev, gpio, "gpio-ir-tx");
> - if (rc < 0)
> - return rc;
> -
> - rc = gpio_direction_output(gpio, !gpio_ir->active_low);
> - if (rc < 0)
> - return rc;
> -
> rc = devm_rc_register_device(&pdev->dev, rcdev);
> if (rc < 0)
> dev_err(&pdev->dev, "failed to register rc device\n");
