Re: [PATCH V2 2/2] drivers: input: keyboard

[Andy Shevchenko]

On Wed, Jan 08, 2020 at 04:46:02PM +0800, Yingjoe Chen wrote:
> On Wed, 2020-01-08 at 14:29 +0800, fengping yu wrote:

> > +	tasklet_init(&keypad->tasklet, kpd_keymap_handler,
> > +		     (unsigned long)keypad);
> > +
> > +	writew((u16)(keypad->key_debounce & KPD_DEBOUNCE_MASK),
> > +		     keypad->base + KP_DEBOUNCE);
> 
> You use a 13 bits mask and set it directly to KP_DEBOUNCE register. Are
> you sure the debounce unit is ms?
> 
> > +
> > +	/* register IRQ */
> > +	err = request_irq(keypad->irqnr, kpd_irq_handler, IRQF_TRIGGER_NONE,
> > +			  KPD_NAME, keypad);
> 
> please consider using devm_request_irq, otherwise you have to free it in
> _remove function.

No, you may not use devm_*_irq() when tasklets are in use. There is a nasty
race condition.

Actually the rule of thumb is to NOT use devm_*_irq() unless you exactly know
what you are doing.

P.S. Why simple not to switch to threaded IRQ handler and drop tasklet? In such
case devm_*_irq() is fine.

-- 
With Best Regards,
Andy Shevchenko