linux-kernel - Re: [PATCH v2 1/7] Input: matrix_keypad - use fsleep for variable delay duration

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Message-ID: <ZypvFmWc3-_N4IZM@google.com>
Date: Tue, 5 Nov 2024 11:16:38 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Markus Burri <markus.burri@...com>
Cc: linux-kernel@...r.kernel.org, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Marek Vasut <marek.vasut@...il.com>, linux-input@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 1/7] Input: matrix_keypad - use fsleep for variable
 delay duration

On Tue, Nov 05, 2024 at 02:03:16PM +0100, Markus Burri wrote:
> The delay is retrieved from a device-tree property, so the duration is
> variable. fsleep guesses the best delay function based on duration.

activate_col() may be called in atomic context, and if fsleep() turns
into usleep_range() or msleep() we are going to have a bad time.

We should either stop using request_any_context_irq() or figure out if
interrupt handler can sleep or not and adjust behavior properly.

> 
> Link: https://www.kernel.org/doc/html/latest/timers/timers-howto.html
> 
> Signed-off-by: Markus Burri <markus.burri@...com>
> ---
>  drivers/input/keyboard/matrix_keypad.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/keyboard/matrix_keypad.c b/drivers/input/keyboard/matrix_keypad.c
> index 3c38bae..9eb6808 100644
> --- a/drivers/input/keyboard/matrix_keypad.c
> +++ b/drivers/input/keyboard/matrix_keypad.c
> @@ -69,7 +69,7 @@ static void activate_col(struct matrix_keypad *keypad, int col, bool on)
>  	__activate_col(keypad, col, on);
>  
>  	if (on && keypad->col_scan_delay_us)
> -		udelay(keypad->col_scan_delay_us);
> +		fsleep(keypad->col_scan_delay_us);
>  }
>  
>  static void activate_all_cols(struct matrix_keypad *keypad, bool on)
> -- 
> 2.39.5
> 

Thanks.

-- 
Dmitry