linux-kernel - Re: [PATCH v3 1/7] gpio: gpio-ep93xx: fix BUG

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Message-ID: <2773b77f3df3f36ab1570d2db07b386cac7cb761.camel@gmail.com>
Date:   Thu, 04 Feb 2021 15:05:28 +0100
From:   Alexander Sverdlin <alexander.sverdlin@...il.com>
To:     nikita.shubin@...uefel.me,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/7] gpio: gpio-ep93xx: fix BUG_ON port F usage

Hi Nikita,

On Thu, 2021-02-04 at 17:00 +0300, nikita.shubin@...uefel.me wrote:
> >  I considered your offer of using array with holes.
> >   
> >  It looks pretty ugly to me, couse it leads to bloated arrays:
> >   
> >  static unsigned char gpio_int_unmasked[EP93XX_GPIO_CHIP_NUM];
> >  static unsigned char gpio_int_enabled[EP93XX_GPIO_CHIP_NUM];
> >  static unsigned char gpio_int_type1[EP93XX_GPIO_CHIP_NUM];
> >  static unsigned char gpio_int_type2[EP93XX_GPIO_CHIP_NUM];
> >  static unsigned char gpio_int_debounce[EP93XX_GPIO_CHIP_NUM];
> >   
> >  /* Port ordering is: A B F */
> >  static const u8 int_type1_register_offset[EP93XX_GPIO_CHIP_NUM]    = { 0x90, 0xac, 0x0, 0x0, 0x0, 0x4c };
> >  static const u8 int_type2_register_offset[EP93XX_GPIO_CHIP_NUM]    = { 0x94, 0xb0, 0x0, 0x0, 0x0, 0x50 };
> >  static const u8 eoi_register_offset[EP93XX_GPIO_CHIP_NUM]    = { 0x98, 0xb4, 0x0, 0x0, 0x0, 0x54 };
> >  static const u8 int_en_register_offset[EP93XX_GPIO_CHIP_NUM]    = { 0x9c, 0xb8, 0x0, 0x0, 0x0, 0x58 };
> >  static const u8 int_debounce_register_offset[EP93XX_GPIO_CHIP_NUM]    = { 0xa8, 0xc4, 0x0, 0x0, 0x0, 0x64 };
> >   
> >  Is this really the thing we want ?
> 
> Even in this form it's less error-prone than to have two
> index-spaces, and hidden conversion from one numbering scheme
> to other.
> 
> Alternatives that I see are:
> 1.
> https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
> 
> 2.
> Embedd the necessary values into struct ep93xx_gpio_bank.
> This option can probably simplify the handling of the names
> for irq chips as well. 
> Thank you very much for your comments, and how about a 3rd option ? :
>  
> It also makes easier to add 'struct irqchip' in following patch.
>  struct ep93xx_gpio_irq_chip {
>        u8 irq_offset;
>        u8 int_unmasked;
>        u8 int_enabled;
>        u8 int_type1;
>        u8 int_type2;
>        u8 int_debounce;
> };
>  
> struct ep93xx_gpio_chip {
>        struct gpio_chip                gc;
>        struct ep93xx_gpio_irq_chip     *eic;
> };
>  
> struct ep93xx_gpio {
>        void __iomem            *base;
>        struct ep93xx_gpio_chip gc[8];
> };
> 
> static const u8 int_register_offset[8]   = { 0x90, 0xac, [5] = 0x4c };
> #define EP93XX_INT_TYPE1_OFFSET        0x00
> #define EP93XX_INT_TYPE2_OFFSET        0x04
> #define EP93XX_INT_EOI_OFFSET          0x08
> #define EP93XX_INT_EN_OFFSET           0x0c
> #define EP93XX_INT_STATUS_OFFSET       0x10
> #define EP93XX_INT_RAW_STATUS_OFFSET   0x14
> #define EP93XX_INT_DEBOUNCE_OFFSET     0x18

Makes sense to me.

-- 
Alexander Sverdlin.