linux-kernel - Re: [PATCH v5 1/7] Input: matrix_keypad - use fsleep for variable delay duration

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Message-ID: <Z71l9046XyjxicFf@google.com>
Date: Mon, 24 Feb 2025 22:40:55 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Manuel Traut <manuel.traut@...com>
Cc: Markus Burri <markus.burri@...com>, 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 v5 1/7] Input: matrix_keypad - use fsleep for variable
 delay duration

On Wed, Feb 19, 2025 at 05:34:49PM +0100, Manuel Traut wrote:
> On Fri, Jan 10, 2025 at 06:49:00AM +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.
> > 
> > see Documentation/timers/delay_sleep_functions.rst
> > 
> > Signed-off-by: Markus Burri <markus.burri@...com>
> 
> Reviewed-by: Manuel Traut <manuel.traut@...com> 

As I mentioned in other review activate_col() may be called in atomic
context where we can not sleep:

"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."

Unfortunately this was completely ignored.

> 
> > ---
> >  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 2a3b3bf..5571d2e 100644
> > --- a/drivers/input/keyboard/matrix_keypad.c
> > +++ b/drivers/input/keyboard/matrix_keypad.c
> > @@ -68,7 +68,7 @@ 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