linux-kernel - Re: [PATCH v1] gpio: mmio: restroe get multiple gpio mask

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Date:   Mon, 24 Apr 2023 22:21:54 +0800
From:   Yan Wang <rk.code@...look.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linus.walleij@...aro.org, brgl@...ev.pl,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] gpio: mmio: restroe get multiple gpio mask



> On Apr 24, 2023, at 21:31, Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> 
> On Sun, Apr 23, 2023 at 05:06:48PM +0800, Yan Wang wrote:
>> Simplify the code,should not modify its logic.
> 
>> Fixes: 761b5c30c206 ("gpio: mmio: replace open-coded for_each_set_bit()")
> 
> What does it fix?
> 
> ...
> 
>> 	for_each_set_bit(i, mask, gc->bgpio_bits) {
>> -		if (test_bit(i, bits))
>> -			*set_mask |= bgpio_line2mask(gc, i);
>> -		else
>> -			*clear_mask |= bgpio_line2mask(gc, i);
>> +		if (*mask == 0)
>> +			break;
> 
> Huh?!
> 
> We never enter here if mask is 0. So, do not add a dead code, please.
> 
> Moreover, in principle mask can be longer than 1 long, this code simply wrong.

You are right.

Because  I use gpiod_set_array_value_cansleep() to set multiple gpios
occur wrong . I restored logic of the original code and found it to be effective. 
So,I try to modify it.

I  recheck logic of  this position that it’s correct. I think  there should be a error in 
Gpiolib. 


> NAK
> 
>> +		if (__test_and_clear_bit(i, mask)) {
>> +			if (test_bit(i, bits))
>> +				*set_mask |= bgpio_line2mask(gc, i);
>> +			else
>> +				*clear_mask |= bgpio_line2mask(gc, i);
>> +		}
>> 	}
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>