* Re: [PATCH v5 2/3] leds: flash: rt8515: Support single-GPIO flash ICs with vin supply
[not found] ` <20260503-expressatt_camera_flash-v5-2-95524506a799@gmail.com>
@ 2026-05-14 10:31 ` Lee Jones
0 siblings, 0 replies; only message in thread
From: Lee Jones @ 2026-05-14 10:31 UTC (permalink / raw)
To: guptarud
Cc: Pavel Machek, Rob Herring, Krzysztof Kozlowski, Conor Dooley,
Linus Walleij, Bjorn Andersson, Konrad Dybcio, Liam Girdwood,
Mark Brown, linux-leds, devicetree, linux-kernel, linux-arm-msm,
phone-devel
On Sun, 03 May 2026, Rudraksha Gupta via B4 Relay wrote:
> From: Rudraksha Gupta <guptarud@gmail.com>
>
> Extend the RT8515 driver to support flash ICs that use only a single
> GPIO for both flash and torch modes (no separate ENT pin), with an
> optional vin regulator that gates power to the flash IC.
>
> When vin-supply is provided, the driver enables the regulator before
> activating the LED and disables it when turning off.
>
> Make ent-gpios optional. When ent-gpios is absent, the driver uses
> enf-gpios for both flash and torch brightness control.
>
> Assisted-by: Claude:claude-opus-4.6
> Reviewed-by: Linus Walleij <linusw@kernel.org>
> Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
> ---
> drivers/leds/flash/leds-rt8515.c | 130 +++++++++++++++++++++++++++++++--------
> 1 file changed, 105 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/leds/flash/leds-rt8515.c b/drivers/leds/flash/leds-rt8515.c
> index f6b439674c03..4459874e6a6c 100644
> --- a/drivers/leds/flash/leds-rt8515.c
> +++ b/drivers/leds/flash/leds-rt8515.c
> @@ -31,6 +31,7 @@
> #include <linux/platform_device.h>
> #include <linux/property.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/workqueue.h>
>
> #include <media/v4l2-flash-led-class.h>
>
> @@ -52,7 +53,7 @@ struct rt8515 {
> struct regulator *reg;
> struct gpio_desc *enable_torch;
> struct gpio_desc *enable_flash;
> - struct timer_list powerdown_timer;
> + struct delayed_work powerdown_work;
> u32 max_timeout; /* Flash max timeout */
> int flash_max_intensity;
> int torch_max_intensity;
> @@ -63,16 +64,50 @@ static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
> return container_of(fled, struct rt8515, fled);
> }
>
> -static void rt8515_gpio_led_off(struct rt8515 *rt)
> +static int rt8515_gpio_led_off(struct rt8515 *rt)
> {
> + int ret;
> +
> gpiod_set_value(rt->enable_flash, 0);
> gpiod_set_value(rt->enable_torch, 0);
> +
> + if (!rt->reg)
> + return 0;
> +
> + /* Disable regulator */
This comment is superfluous.
> + ret = regulator_is_enabled(rt->reg);
> + if (ret < 0)
> + return ret;
Initialise ret to 0 and return ret then you can remove this branch.
> + if (ret > 0)
> + return regulator_disable(rt->reg);
> +
> + return 0;
> }
>
> -static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
> - int brightness)
> +static int rt8515_gpio_brightness_commit(struct rt8515 *rt,
> + struct gpio_desc *gpiod,
> + int brightness)
Use 100-chars to avoid this cramping.
> {
> int i;
> + int ret;
> +
> + /*
> + * Reset the IC to start brightness from zero,
> + * then re-enable and pulse to the desired level.
> + */
> + ret = rt8515_gpio_led_off(rt);
> + if (ret)
> + return ret;
> +
> + /* IC needs time to reset its brightness counter */
> + usleep_range(100, 200);
> +
> + /* Enable regulator */
As above.
> + if (rt->reg) {
> + ret = regulator_enable(rt->reg);
> + if (ret)
> + return ret;
> + }
>
> /*
> * Toggling a GPIO line with a small delay increases the
> @@ -84,6 +119,8 @@ static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
> gpiod_set_value(gpiod, 1);
> udelay(1);
> }
> +
> + return 0;
> }
>
> /* This is setting the torch light level */
> @@ -92,23 +129,38 @@ static int rt8515_led_brightness_set(struct led_classdev *led,
> {
> struct led_classdev_flash *fled = lcdev_to_flcdev(led);
> struct rt8515 *rt = to_rt8515(fled);
> + int ret = 0;
>
> mutex_lock(&rt->lock);
>
> if (brightness == LED_OFF) {
> /* Off */
> - rt8515_gpio_led_off(rt);
> + ret = rt8515_gpio_led_off(rt);
> + if (ret)
> + goto out;
> } else if (brightness < RT8515_TORCH_MAX) {
> - /* Step it up to movie mode brightness using the flash pin */
> - rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
> + /*
> + * Step it up to movie mode brightness.
> + * If there is no separate torch pin, use the flash pin
> + * for torch as well.
> + */
> + ret = rt8515_gpio_brightness_commit(rt,
> + rt->enable_torch ?: rt->enable_flash, brightness);
> + if (ret)
> + goto out;
> } else {
> - /* Max torch brightness requested */
> - gpiod_set_value(rt->enable_torch, 1);
> + /*
> + * Max torch brightness requested.
> + * If there is no separate torch pin, use the flash pin
> + * for torch as well.
> + */
> + gpiod_set_value(rt->enable_torch ?: rt->enable_flash, 1);
What does 1 mean in this context? Maybe define it so it's clear.
> }
>
> +out:
> mutex_unlock(&rt->lock);
>
> - return 0;
> + return ret;
> }
>
> static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
> @@ -117,27 +169,34 @@ static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
> struct rt8515 *rt = to_rt8515(fled);
> struct led_flash_setting *timeout = &fled->timeout;
> int brightness = rt->flash_max_intensity;
> + int ret = 0;
>
> mutex_lock(&rt->lock);
>
> if (state) {
> /* Enable LED flash mode and set brightness */
> - rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
> + ret = rt8515_gpio_brightness_commit(rt, rt->enable_flash, brightness);
> + if (ret)
> + goto out;
> +
> /* Set timeout */
> - mod_timer(&rt->powerdown_timer,
> - jiffies + usecs_to_jiffies(timeout->val));
> + schedule_delayed_work(&rt->powerdown_work,
> + usecs_to_jiffies(timeout->val));
> } else {
> - timer_delete_sync(&rt->powerdown_timer);
> + cancel_delayed_work(&rt->powerdown_work);
Would it be safer to use 'cancel_delayed_work_sync()' here? The previous
implementation used the synchronous 'timer_delete_sync()'. Swapping to an
asynchronous cancellation might introduce a race condition if the work is
already executing.
> /* Turn the LED off */
> - rt8515_gpio_led_off(rt);
> + ret = rt8515_gpio_led_off(rt);
> + if (ret)
> + goto out;
> }
>
> fled->led_cdev.brightness = LED_OFF;
> /* After this the torch LED will be disabled */
>
> +out:
> mutex_unlock(&rt->lock);
>
> - return 0;
> + return ret;
> }
>
> static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
> @@ -145,7 +204,7 @@ static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
> {
> struct rt8515 *rt = to_rt8515(fled);
>
> - *state = timer_pending(&rt->powerdown_timer);
> + *state = delayed_work_pending(&rt->powerdown_work);
>
> return 0;
> }
> @@ -163,12 +222,18 @@ static const struct led_flash_ops rt8515_flash_ops = {
> .timeout_set = rt8515_led_flash_timeout_set,
> };
>
> -static void rt8515_powerdown_timer(struct timer_list *t)
> +static void rt8515_powerdown_work(struct work_struct *work)
> {
> - struct rt8515 *rt = timer_container_of(rt, t, powerdown_timer);
> + struct rt8515 *rt = container_of(work, struct rt8515, powerdown_work.work);
> + int ret;
>
> /* Turn the LED off */
> - rt8515_gpio_led_off(rt);
> + mutex_lock(&rt->lock);
> + ret = rt8515_gpio_led_off(rt);
> + mutex_unlock(&rt->lock);
> +
> + if (ret)
> + dev_err(rt->dev, "failed to turn off LED (%d)\n", ret);
> }
>
> static void rt8515_init_flash_timeout(struct rt8515 *rt)
> @@ -298,12 +363,22 @@ static int rt8515_probe(struct platform_device *pdev)
> return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
> "cannot get ENF (enable flash) GPIO\n");
>
> - /* ENT - Enable Torch line */
> - rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
> + /* ENT - Enable Torch line (optional for single-GPIO flash ICs) */
> + rt->enable_torch = devm_gpiod_get_optional(dev, "ent", GPIOD_OUT_LOW);
> if (IS_ERR(rt->enable_torch))
> return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
> "cannot get ENT (enable torch) GPIO\n");
The user doesn't care about 'ENT'.
"Failed to obtain the Enable Torch GPIO"
> +
> + /* Optional VIN supply */
Doesn't the function call already say this?
> + rt->reg = devm_regulator_get_optional(dev, "vin");
> + if (IS_ERR(rt->reg)) {
> + ret = PTR_ERR(rt->reg);
> + if (ret != -ENODEV)
> + return dev_err_probe(dev, ret,
> + "failed to get vin supply\n");
Why are we erroring out on an optional regulator?
> + rt->reg = NULL;
> + }
> +
> child = device_get_next_child_node(dev, NULL);
> if (!child) {
> dev_err(dev,
> @@ -328,12 +403,17 @@ static int rt8515_probe(struct platform_device *pdev)
> dev_warn(dev,
> "flash-max-timeout-us property missing\n");
> }
> - timer_setup(&rt->powerdown_timer, rt8515_powerdown_timer, 0);
> + INIT_DELAYED_WORK(&rt->powerdown_work, rt8515_powerdown_work);
> rt8515_init_flash_timeout(rt);
>
> fled->ops = &rt8515_flash_ops;
>
> - led->max_brightness = rt->torch_max_intensity;
> + /*
> + * If there is no separate torch pin, use the flash max intensity
Drop the "the".
> + * as the max brightness instead.
> + */
> + led->max_brightness = rt->enable_torch ?
> + rt->torch_max_intensity : rt->flash_max_intensity;
> led->brightness_set_blocking = rt8515_led_brightness_set;
> led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
>
> @@ -372,7 +452,7 @@ static void rt8515_remove(struct platform_device *pdev)
> struct rt8515 *rt = platform_get_drvdata(pdev);
>
> rt8515_v4l2_flash_release(rt);
> - timer_delete_sync(&rt->powerdown_timer);
> + cancel_delayed_work_sync(&rt->powerdown_work);
> mutex_destroy(&rt->lock);
> }
>
>
> --
> 2.54.0
>
>
--
Lee Jones
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