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Input: tegra-kbc - add ghost key filter

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Add ghost key filtering support for the Nvidia Tegra matrix keyboard.

Signed-off-by: Rakesh Iyer <riyer@nvidia.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Rakesh Iyer 2011-04-27 23:18:15 -07:00 committed by Dmitry Torokhov
parent 5c9db64888
commit 34abeeb235
2 changed files with 37 additions and 0 deletions
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1
arch/arm/mach-tegra/include/mach/kbc.h
View file

@ -58,5 +58,6 @@ struct tegra_kbc_platform_data {
bool wakeup;
bool use_fn_map;
bool use_ghost_filter;
};
#endif

36
drivers/input/keyboard/tegra-kbc.c
View file

@ -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++) {
@ -284,6 +287,34 @@ static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
val >>= 8;
}
/*
* 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 key presses 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 key presses 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);