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Commit 7763481a authored by Frank Schaefer's avatar Frank Schaefer Committed by Mauro Carvalho Chehab
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[media] em28xx: add debouncing mechanism for GPI-connected buttons 



So far, the driver only supports a snapshot button which is assigned to
register 0x0c bit 5. This special port has a built-in debouncing mechanism.
For buttons connected to ordinary GPI ports, this patch implements a software
debouncing mechanism.

Signed-off-by: default avatarFrank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent f5222609

drivers/media/usb/em28xx/em28xx-input.c

+19 −11
Original line number Diff line number Diff line
@@ -479,7 +479,7 @@ static void em28xx_query_buttons(struct work_struct *work) 
		container_of(work, struct em28xx, buttons_query_work.work);

	u8 i, j;

	int regval;

	bool pressed;

	bool is_pressed, was_pressed;



	/* Poll and evaluate all addresses */

	for (i = 0; i < dev->num_button_polling_addresses; i++) {
@@ -497,12 +497,21 @@ static void em28xx_query_buttons(struct work_struct *work) 
				j++;

				continue;

			}

			/* Determine if button is pressed */

			pressed = regval & button->mask;

			if (button->inverted)

				pressed = !pressed;

			/* Determine if button is and was pressed last time */

			is_pressed = regval & button->mask;

			was_pressed = dev->button_polling_last_values[i]

				       & button->mask;

			if (button->inverted) {

				is_pressed = !is_pressed;

				was_pressed = !was_pressed;

			}

			/* Clear button state (if needed) */

			if (is_pressed && button->reg_clearing)

				em28xx_write_reg(dev, button->reg_clearing,

						 (~regval & button->mask)

						    | (regval & ~button->mask));

			/* Handle button state */

			if (!pressed) {

			if (!is_pressed || was_pressed) {

				j++;

				continue;

			}
@@ -518,14 +527,11 @@ static void em28xx_query_buttons(struct work_struct *work) 
			default:

				WARN_ONCE(1, "BUG: unhandled button role.");

			}

			/* Clear button state (if needed) */

			if (button->reg_clearing)

				em28xx_write_reg(dev, button->reg_clearing,

						 (~regval & button->mask)

						    | (regval & ~button->mask));

			/* Next button */

			j++;

		}

		/* Save current value for comparison during the next polling */

		dev->button_polling_last_values[i] = regval;

	}

	/* Schedule next poll */

	schedule_delayed_work(&dev->buttons_query_work,
@@ -611,6 +617,8 @@ static void em28xx_init_buttons(struct em28xx *dev) 


	/* Start polling */

	if (dev->num_button_polling_addresses) {

		memset(dev->button_polling_last_values, 0,

					       EM28XX_NUM_BUTTON_ADDRESSES_MAX);

		INIT_DELAYED_WORK(&dev->buttons_query_work,

							  em28xx_query_buttons);

		schedule_delayed_work(&dev->buttons_query_work,

drivers/media/usb/em28xx/em28xx.h

+1 −0
Original line number Diff line number Diff line
@@ -669,6 +669,7 @@ struct em28xx { 
	/* Button state polling */

	struct delayed_work buttons_query_work;

	u8 button_polling_addresses[EM28XX_NUM_BUTTON_ADDRESSES_MAX];

	u8 button_polling_last_values[EM28XX_NUM_BUTTON_ADDRESSES_MAX];

	u8 num_button_polling_addresses;

	/* Snapshot button input device */

	char snapshot_button_path[30];	/* path of the input dev */