linux-kernel - Re: [PATCH v1 1/3] mux: gpio: Use bitmap API instead of direct assignment

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Date:   Tue, 30 Mar 2021 18:10:58 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/3] mux: gpio: Use bitmap API instead of direct
 assignment

Hi!

On 2021-03-26 18:23, Andy Shevchenko wrote:
> Assigning bitmaps like it's done in the driver might be error prone.
> Fix this by using bitmap API.

A bit strongly worded perhaps, since the size of a mux chip with
anywhere near 31 inputs and 2^31 possible selections is a bit
ridiculous. Please send a photo of that HW if someone is producing
one :-)

But there's always the someone-borrows-code-factor, so I guess it's
fine as-is.

> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/mux/gpio.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mux/gpio.c b/drivers/mux/gpio.c
> index 02c1f2c014e8..891ee0274733 100644
> --- a/drivers/mux/gpio.c
> +++ b/drivers/mux/gpio.c
> @@ -6,7 +6,7 @@
>   *
>   * Author: Peter Rosin <peda@...ntia.se>
>   */
> -

Nit, please keep the empty line here. With that,

Acked-by: Peter Rosin <peda@...ntia.se>

And please send directly to Greg, that would be excellent, thanks!

Cheers,
Peter

> +#include <linux/bitmap.h>
>  #include <linux/err.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/module.h>
> @@ -23,8 +23,9 @@ static int mux_gpio_set(struct mux_control *mux, int state)
>  {
>  	struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
>  	DECLARE_BITMAP(values, BITS_PER_TYPE(state));
> +	u32 value = state;
>  
> -	values[0] = state;
> +	bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));
>  
>  	gpiod_set_array_value_cansleep(mux_gpio->gpios->ndescs,
>  				       mux_gpio->gpios->desc,
> @@ -71,7 +72,7 @@ static int mux_gpio_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  	WARN_ON(pins != mux_gpio->gpios->ndescs);
> -	mux_chip->mux->states = 1 << pins;
> +	mux_chip->mux->states = BIT(pins);
>  
>  	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
>  	if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
>