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

On Wed, Jan 08, 2020 at 01:26:09PM +0200, Andy Shevchenko wrote:

On Wed, Jan 08, 2020 at 04:46:02PM +0800, Yingjoe Chen wrote:

quoted

On Wed, 2020-01-08 at 14:29 +0800, fengping yu wrote:

quoted

quoted

+	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?

quoted

+
+	/* 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.

Actually, we are simply reading iomem data and forward it to input
subsystem, there is no need to use threaded interrupt nor the tasklet.

Thanks.

-- 
Dmitry

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel