linux-kernel - Re: [PATCH v2] gpio: gpiolib: clear the array

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Date:   Thu, 4 May 2023 17:36:56 +0800
From:   Yan Wang <rk.code@...look.com>
To:     andy.shevchenko@...il.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 v2] gpio: gpiolib: clear the array_info's memory space

On 4/26/2023 10:42 PM, andy.shevchenko@...il.com wrote:
> Sun, Apr 23, 2023 at 09:59:43PM +0800, Yan Wang kirjoitti:
>> if hardware number different to array index,it needs to clear to points
>> memory space if the array_info have been assigned a value.
> Can you explain a bit more what's going on there?
>
> ...
Hi Andy,

I use gpiod_get_array() to get a gpio array form the node of DTS.

the node is as follows:
...
gpios = <&gpio1 0 0>, <&gpio1 10 0>;
...

First scan pin-0 of gpio1,its index and hardware number are 0,

if (descs->ndescs == 0 && gpio_chip_hwgpio(desc) == 0) {
     ...
     descs->info = array_info.
}

Then scan pin-10 , its index is 1 ,but hardware number is 10 .

if (gpio_chip_hwgpio(desc) != descs->ndescs) {
     array_info = NULL;
}
just set array_info = NULL, Should the array_info point to memory be 
cleared ?

if not cleared ,I use the gpiod_set_array_value_cansleep() to pull up or 
down pin-10 is invalid.

I found that the set_mask and get_mask vlaues of descs->info are seted 
0x03 in gpiod_get_array(),
I think 0x401 is their correct value.

Thank you for review.
>> if (bitmap_full(array_info->get_mask, descs->ndescs)) {
>> + /*clear descs->info*/
>> + memset(array_info, 0, sizeof(struct gpio_array));
>> array_info = NULL;
> ...
>
>> }