linux-kernel - Re: [PATCH 2/2] gpio: davinci: Remove gpio2regs function to accommodate multi instances

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Message-ID: <CACRpkdYzq0o3Y2BoccPVK4Ro1NWdspqcF12GO0c7wwhz3WPVoA@mail.gmail.com>
Date:   Wed, 11 Jan 2017 16:53:04 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Keerthy <j-keerthy@...com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Tero Kristo <t-kristo@...com>
Subject: Re: [PATCH 2/2] gpio: davinci: Remove gpio2regs function to
 accommodate multi instances

On Wed, Jan 11, 2017 at 1:40 PM, Keerthy <j-keerthy@...com> wrote:
> On Wednesday 11 January 2017 04:34 PM, Linus Walleij wrote:
>> On Wed, Jan 4, 2017 at 9:26 AM, Keerthy <j-keerthy@...com> wrote:
>>
>>> gpio2regs is written making an assumption that driver supports only
>>> one instance of gpio controller. Removing this and adding a generic
>>> array so as to support multiple instances of gpio controllers.
>>>
>>> Signed-off-by: Keerthy <j-keerthy@...com>
>>
>>
>>> -               regs = gpio2regs(base);
>>> +               regs = gpio_base + offset_array[i];
>>
>>
>> I understand this.
>>
>>> -       struct davinci_gpio_regs __iomem *g = gpio2regs(hw);
>>> +       struct davinci_gpio_controller *chips =
>>> +                               (struct davinci_gpio_controller
>>> *)d->host_data;
>>> +       struct davinci_gpio_regs __iomem *g = chips[hw / 32].regs;
>>
>>
>> And this, if each instans has 32 GPIOs.
>>
>>> -               g = gpio2regs(0);
>>> +               g = chips[0].regs;
>>
>>
>> Also makes sense.
>>
>>> -               g = gpio2regs(gpio);
>>> +               g = chips[bank / 2].regs;
>>
>>
>> But what is this? I don't understand that /2 at all. Please insert a
>> comment explaining it so I can figure it out. Are there two banks
>> per instance?
>
>
> Yes! There are register sets for 32 GPIOs. 2 banks of 16 GPIOs are covered
> by each set of registers hence /2. Shall i add a comment and send this patch
> alone separately?

Yeah.

I am currently confused by several patch sets for davinci in my inbox,
can you rebase on my devel branch when I push it and resend
*all* you have cooking for DaVinci?

Yours,
Linus Walleij