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

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Message-ID: <KL1PR01MB54484CA1950D9468D0228C08E6759@KL1PR01MB5448.apcprd01.prod.exchangelabs.com>
Date:   Fri, 12 May 2023 15:37:13 +0800
From:   Yan Wang <rk.code@...look.com>
To:     Andy Shevchenko <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

Polite ping

On 5/4/2023 10:15 PM, Yan Wang wrote:
>
>> On May 4, 2023, at 19:36, Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>>
>> On Thu, May 4, 2023 at 12:38 PM Yan Wang <rk.code@...look.com> wrote:
>>> 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?
>> ...
>>
>>> 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 ?
>> This is a good question. The entire algorithm is a bit difficult to
>> understand from the first glance. I need some time to check it myself.
> Looking forward to your test results.
>>> if not cleared ,I use the gpiod_set_array_value_cansleep() to pull up or
>>> down pin-10 is invalid.
>> I'm not sure I follow. The array operations are against the given
>> array of the descriptors. If you ask to have that operation done, the
>> all descriptors in the array should be considered.
>>
>>> I found that the set_mask and get_mask vlaues of descs->info are seted
>>> 0x03 in gpiod_get_array(),
>> Yes, this mask is for the argument. The 0x03 is the correct one.
>>
>>> I think 0x401 is their correct value.
>> No. You have an array of two elements, and not 11.
> Due to hardware number are 10 and 0 , so this mask is 0x401（bit10 and bit0 are 1）.
>
>>>>> if (bitmap_full(array_info->get_mask, descs->ndescs)) {
>>>>> + /*clear descs->info*/
>>>>> + memset(array_info, 0, sizeof(struct gpio_array));
>>>>> array_info = NULL;
>>>>> }
>>
>> -- 
>> With Best Regards,
>> Andy Shevchenko