Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 22 Apr 2024 17:19:15 +0800 | Subject | Re: [PATCH v7 3/3] pinctrl: nuvoton: Add ma35d1 pinctrl and GPIO driver | From | Jacky Huang <> |
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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
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