On Thu, Apr 21, 2011 at 03:10:15PM -0700, riyer@xxxxxxxxxx wrote:
> From: Rakesh Iyer <riyer@xxxxxxxxxx>
>
> Add ghost key filtering support for the Nvidia Tegra matrix keyboard.
>
> Signed-off-by: Rakesh Iyer <riyer@xxxxxxxxxx>
> ---
> v2: Incorporated Henrik Rydberg's suggestions.
> v1: Do not report keypresses when matrix keyboard encounters key ghosting.
>
> arch/arm/mach-tegra/include/mach/kbc.h | 1 +
> drivers/input/keyboard/tegra-kbc.c | 36 ++++++++++++++++++++++++++++++++
> 2 files changed, 37 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mach-tegra/include/mach/kbc.h b/arch/arm/mach-tegra/include/mach/kbc.h
> index 04c7798..bd99744 100644
> --- a/arch/arm/mach-tegra/include/mach/kbc.h
> +++ b/arch/arm/mach-tegra/include/mach/kbc.h
> @@ -58,5 +58,6 @@ struct tegra_kbc_platform_data {
>
> bool wakeup;
> bool use_fn_map;
> + bool use_ghost_filter;
> };
> #endif
> diff --git a/drivers/input/keyboard/tegra-kbc.c b/drivers/input/keyboard/tegra-kbc.c
> index 99ce903..56f6668 100644
> --- a/drivers/input/keyboard/tegra-kbc.c
> +++ b/drivers/input/keyboard/tegra-kbc.c
> @@ -72,6 +72,7 @@ struct tegra_kbc {
> unsigned int repoll_dly;
> unsigned long cp_dly_jiffies;
> bool use_fn_map;
> + bool use_ghost_filter;
> const struct tegra_kbc_platform_data *pdata;
> unsigned short keycode[KBC_MAX_KEY * 2];
> unsigned short current_keys[KBC_MAX_KPENT];
> @@ -260,6 +261,8 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
> unsigned int num_down = 0;
> unsigned long flags;
> bool fn_keypress = false;
> + bool key_in_same_row = false;
> + bool key_in_same_col = false;
>
> spin_lock_irqsave(&kbc->lock, flags);
> for (i = 0; i < KBC_MAX_KPENT; i++) {
> @@ -285,6 +288,34 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
> }
>
> /*
> + * Matrix keyboard designs are prone to keyboard ghosting.
> + * Ghosting occurs if there are 3 keys such that -
> + * any 2 of the 3 keys share a row, and any 2 of them share a column.
> + * If so ignore the keypresses for this iteration.
> + */
> + if ((kbc->use_ghost_filter) && (num_down >= 3)) {
> + for (i = 0; i < num_down; i++) {
> + unsigned int j;
> + u8 curr_col = scancodes[i] & 0x07;
> + u8 curr_row = scancodes[i] >> KBC_ROW_SHIFT;
> +
> + /*
> + * Find 2 keys such that one key is in the same row
> + * and the other is in the same column as the i-th key.
> + */
> + for (j = i + 1; j < num_down; j++) {
> + u8 col = scancodes[j] & 0x07;
> + u8 row = scancodes[j] >> KBC_ROW_SHIFT;
> +
> + if (col == curr_col)
> + key_in_same_col = true;
> + if (row == curr_row)
> + key_in_same_row = true;
> + }
> + }
> + }
> +
> + /*
> * If the platform uses Fn keymaps, translate keys on a Fn keypress.
> * Function keycodes are KBC_MAX_KEY apart from the plain keycodes.
> */
> @@ -297,6 +328,10 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
>
> spin_unlock_irqrestore(&kbc->lock, flags);
>
> + /* Ignore the keypresses for this iteration? */
> + if (key_in_same_col && key_in_same_row)
> + return;
> +
> tegra_kbc_report_released_keys(kbc->idev,
> kbc->current_keys, kbc->num_pressed_keys,
> keycodes, num_down);
> @@ -652,6 +687,7 @@ static int __devinit tegra_kbc_probe(struct platform_device *pdev)
> input_dev->keycodemax *= 2;
>
> kbc->use_fn_map = pdata->use_fn_map;
> + kbc->use_ghost_filter = pdata->use_ghost_filter;
> keymap_data = pdata->keymap_data ?: &tegra_kbc_default_keymap_data;
> matrix_keypad_build_keymap(keymap_data, KBC_ROW_SHIFT,
> input_dev->keycode, input_dev->keybit);
> --
> 1.7.1
>
Reviewed-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
Thanks,
Henrik
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