From: Jacky Huang <ychuang570808@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: linus.walleij@linaro.org, robh+dt@kernel.org,
krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
p.zabel@pengutronix.de, j.neuschaefer@gmx.net,
linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
ychuang3@nuvoton.com, schung@nuvoton.com
Subject: Re: [PATCH v7 3/3] pinctrl: nuvoton: Add ma35d1 pinctrl and GPIO driver
Date: Mon, 22 Apr 2024 17:19:15 +0800 [thread overview]
Message-ID: <843c3c2a-2f46-4d49-aed4-ad07ebcb7b27@gmail.com> (raw)
In-Reply-To: <CAHp75VfMb_=XKoQNbbVphLg-eQgc6eJbZOW36g_hU=-iK2bSOQ@mail.gmail.com>
Dear Andy,
On 2024/4/22 下午 04:16, Andy Shevchenko wrote:
> On Mon, Apr 22, 2024 at 7:10 AM Jacky Huang <ychuang570808@gmail.com> wrote:
>> On 2024/4/10 下午 04:54, Andy Shevchenko wrote:
> ...
>
>>>> +#define MA35_GP_MODE_MASK_WIDTH 2
>>>> +
>>>> +#define MA35_GP_SLEWCTL_MASK_WIDTH 2
>>> I looked at the code how you use these... Oh, please switch to FIELD_GET() /
>>> FIELD_PREP() (don't forget to include bitfield.h)
>>>
>>> ...
>>>
>>> ...
>>>> + regval &= ~GENMASK(setting->shift + MA35_MFP_BITS_PER_PORT - 1,
>>>> + setting->shift);
>>> This will generate an awful code. Use respective FIELD_*() macros.
>>>
>>> ...
>>>
>>>> + regval &= ~GENMASK(gpio * MA35_GP_MODE_MASK_WIDTH - 1,
>>>> + gpio * MA35_GP_MODE_MASK_WIDTH);
>>>> + regval |= mode << gpio * MA35_GP_MODE_MASK_WIDTH;
>>> Ditto.
>>>
>>> ...
>>>
>>>> + regval &= GENMASK(gpio * MA35_GP_MODE_MASK_WIDTH - 1,
>>>> + gpio * MA35_GP_MODE_MASK_WIDTH);
>>>> +
>>>> + return regval >> gpio * MA35_GP_MODE_MASK_WIDTH;
>>> Ditto.
> ...
>
>> Allow me to remove irrelevant parts.
>>
>> I attempted to follow your advice and use FIELD_GET() and FIELD_PREP(),
>> but found
>> it impractical. The reason is that these two macros require their 'mask'
>> argument
>> to be a constant, otherwise compilation errors occur, which is the issue
>> I encountered.
>> Since the mask here is calculated and not a constant, compilation errors
>> occur.
>>
>> Taking MA35_GP_REG_MODE as an example, within 32 bits, every 2 bits
>> represent
>> the mode of a GPIO pin, and the mask is obtained by GENMASK(gpio * 2 -1,
>> gpio * 2),
> This is not good for the compiler, it can't figure out (at least in
> some _supported_ by Linux kernel versions on some architectures) that
> GENMASK can be constant here just left-shifted by arbitrary bits.
>
>> where the 'gpio' argument is a variable, not a constant, leading to
>> compilation
>> errors.
>>
>> Due to this reason, I will leave this part unchanged, or do you have any
>> other suggestions?
> If you need non-constant field_get()/field_prep(), add a new patch
> that moves them from drivers/iio/temperature/mlx90614.c (and there are
> more custom implementations:
> https://elixir.bootlin.com/linux/latest/A/ident/field_get) to the
> bitfield.h and use them in your code.
>
Thank you. It works for me. I will adopt the approach used in mlx90614.c.
Best Regards,
Jacky Huang
prev parent reply other threads:[~2024-04-22 9:19 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-09 9:56 [PATCH v7 0/3] Add support for nuvoton ma35d1 pin control Jacky Huang
2024-04-09 9:56 ` [PATCH v7 1/3] dt-bindings: reset: Add syscon to nuvoton ma35d1 system-management node Jacky Huang
2024-04-09 9:56 ` [PATCH v7 2/3] dt-bindings: pinctrl: Document nuvoton ma35d1 pin control Jacky Huang
2024-04-09 16:29 ` Rob Herring
2024-04-10 2:53 ` Jacky Huang
2024-04-09 9:56 ` [PATCH v7 3/3] pinctrl: nuvoton: Add ma35d1 pinctrl and GPIO driver Jacky Huang
2024-04-10 8:54 ` Andy Shevchenko
2024-04-15 1:18 ` Jacky Huang
2024-04-22 4:10 ` Jacky Huang
2024-04-22 8:16 ` Andy Shevchenko
2024-04-22 9:19 ` Jacky Huang [this message]
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