linux-kernel - Re: [PATCH 1/2] Input: omap-keypad: Fix keyboard debounce configuration

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Date:   Mon, 3 Dec 2018 11:25:11 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, Axel Haslam <axelhaslam@...com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Illia Smyrnov <illia.smyrnov@...com>,
        Marcel Partap <mpartap@....net>,
        Merlijn Wajer <merlijn@...zup.org>,
        Michael Scott <hashcode0f@...il.com>,
        NeKit <nekit1000@...il.com>, Pavel Machek <pavel@....cz>,
        Sebastian Reichel <sre@...nel.org>
Subject: Re: [PATCH 1/2] Input: omap-keypad: Fix keyboard debounce
 configuration

On Sun, Dec 02, 2018 at 05:29:32PM -0800, Tony Lindgren wrote:
> I noticed that the Android v3.0.8 kernel on droid4 is using different
> keypad values from the mainline kernel and does not have issues with
> keys occasionally being stuck until pressed again. Turns out there was
> an earlier patch posted to fix this as "Input: omap-keypad: errata i689:
> Correct debounce time", but it was never reposted to fix use macros
> for timing calculations.
> 
> This updated version is using macros, and also fixes the use of the
> input clock rate to use 32768KiHz instead of 32000KiHz. And we want to
> use the known good Android kernel values of 3 and 6 instead of 2 and 6
> in the earlier patch.
> 
> Cc: Axel Haslam <axelhaslam@...com>
> Cc: Felipe Balbi <felipe.balbi@...ux.intel.com>
> Cc: Illia Smyrnov <illia.smyrnov@...com>
> Cc: Marcel Partap <mpartap@....net>
> Cc: Merlijn Wajer <merlijn@...zup.org>
> Cc: Michael Scott <hashcode0f@...il.com>
> Cc: NeKit <nekit1000@...il.com>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Sebastian Reichel <sre@...nel.org>
> Reported-by: Pavel Machek <pavel@....cz>
> Signed-off-by: Tony Lindgren <tony@...mide.com>

Applied, thank you.

> ---
>  drivers/input/keyboard/omap4-keypad.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/keyboard/omap4-keypad.c b/drivers/input/keyboard/omap4-keypad.c
> --- a/drivers/input/keyboard/omap4-keypad.c
> +++ b/drivers/input/keyboard/omap4-keypad.c
> @@ -60,8 +60,18 @@
>  
>  /* OMAP4 values */
>  #define OMAP4_VAL_IRQDISABLE		0x0
> -#define OMAP4_VAL_DEBOUNCINGTIME	0x7
> -#define OMAP4_VAL_PVT			0x7
> +
> +/*
> + * Errata i689: If a key is released for a time shorter than debounce time,
> + * the keyboard will idle and never detect the key release. The workaround
> + * is to use at least a 12ms debounce time. See omap5432 TRM chapter
> + * "26.4.6.2 Keyboard Controller Timer" for more information.
> + */
> +#define OMAP4_KEYPAD_PTV_DIV_128        0x6
> +#define OMAP4_KEYPAD_DEBOUNCINGTIME_MS(dbms, ptv)     \
> +	((((dbms) * 1000) / ((1 << ((ptv) + 1)) * (1000000 / 32768))) - 1)
> +#define OMAP4_VAL_DEBOUNCINGTIME_16MS					\
> +	OMAP4_KEYPAD_DEBOUNCINGTIME_MS(16, OMAP4_KEYPAD_PTV_DIV_128)
>  
>  enum {
>  	KBD_REVISION_OMAP4 = 0,
> @@ -181,9 +191,9 @@ static int omap4_keypad_open(struct input_dev *input)
>  
>  	kbd_writel(keypad_data, OMAP4_KBD_CTRL,
>  			OMAP4_DEF_CTRL_NOSOFTMODE |
> -			(OMAP4_VAL_PVT << OMAP4_DEF_CTRL_PTV_SHIFT));
> +			(OMAP4_KEYPAD_PTV_DIV_128 << OMAP4_DEF_CTRL_PTV_SHIFT));
>  	kbd_writel(keypad_data, OMAP4_KBD_DEBOUNCINGTIME,
> -			OMAP4_VAL_DEBOUNCINGTIME);
> +			OMAP4_VAL_DEBOUNCINGTIME_16MS);
>  	/* clear pending interrupts */
>  	kbd_write_irqreg(keypad_data, OMAP4_KBD_IRQSTATUS,
>  			 kbd_read_irqreg(keypad_data, OMAP4_KBD_IRQSTATUS));
> -- 
> 2.19.2

-- 
Dmitry