Hi Duje,
thanks for your patch!
On Thu, Jan 18, 2024 at 6:33 PM Duje Mihanović <duje.mihanovic@xxxxxxxx> wrote:
> Add driver for the Kinetic KTD2801 backlight driver.>
> Signed-off-by: Duje Mihanović <duje.mihanovic@xxxxxxxx>
Add some commit message?
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/of.h>
I don't think you need <linux/of.h>, the compatible table works without
that (is in the device driver core).
> +/* These values have been extracted from Samsung's driver. */
> +#define KTD2801_EXPRESSWIRE_DETECT_DELAY_US 150
> +#define KTD2801_EXPRESSWIRE_DETECT_US 270
> +#define KTD2801_LOW_BIT_HIGH_TIME_US 5
> +#define KTD2801_LOW_BIT_LOW_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_US)
> +#define KTD2801_HIGH_BIT_LOW_TIME_US 5
> +#define KTD2801_HIGH_BIT_HIGH_TIME_US (4 * KTD2801_HIGH_BIT_LOW_TIME_US)
> +#define KTD2801_DATA_START_US 5
> +#define KTD2801_END_OF_DATA_LOW_US 10
> +#define KTD2801_END_OF_DATA_HIGH_US 350
> +#define KTD2801_PWR_DOWN_DELAY_US 2600
> +
> +#define KTD2801_DEFAULT_BRIGHTNESS 100
> +#define KTD2801_MAX_BRIGHTNESS 255
> +
> +struct ktd2801_backlight {
> + struct backlight_device *bd;
> + struct gpio_desc *gpiod;
> + bool was_on;
> +};
> +
> +static int ktd2801_update_status(struct backlight_device *bd)
> +{
> + struct ktd2801_backlight *ktd2801 = bl_get_data(bd);
> + u8 brightness = (u8) backlight_get_brightness(bd);
> +
> + if (backlight_is_blank(bd)) {
> + gpiod_set_value(ktd2801->gpiod, 0);
> + udelay(KTD2801_PWR_DOWN_DELAY_US);
That's 2600 us, a pretty long delay in a hard loop or delay timer!
Can you use usleep_range() instead, at least for this one?
> + for (int i = 0; i < 8; i++) {
> + u8 next_bit = (brightness & 0x80) >> 7;
I would just:
#include <linux/bits.h>
bool next_bit = !!(brightness & BIT(7));
Yours,
Linus Walleij
