linux-kernel - Re: [PATCH v4 3/3] bus: ts-nbus: use bitmap_set

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Message-ID: <b4e3260d-ecf9-4a51-85c1-889d7741d287@baylibre.com>
Date: Wed, 11 Jun 2025 15:26:50 -0500
From: David Lechner <dlechner@...libre.com>
To: Sebastien Bourdelin <sebastien.bourdelin@...oirfairelinux.com>,
 Arnd Bergmann <arnd@...db.de>, linux-arm-kernel@...ts.infradead.org
Cc: Linus Walleij <linus.walleij@...aro.org>,
 Bartosz Golaszewski <brgl@...ev.pl>, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org, Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v4 3/3] bus: ts-nbus: use bitmap_set_value8()

On 6/11/25 3:18 PM, David Lechner wrote:
> Use bitmap_set_value8() instead of accessing the bitmap directly.
> 
> Accessing the bitmap directly is not considered good practice. We now
> have a helper function that can be used instead, so let's use it.
> 
> The bitmap has to be zero-initialized now to avoid a compiler warning
> since bitmap_set_value8() does read/modify/write rather than just the
> write that this is replacing.
> 
> Suggested-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: David Lechner <dlechner@...libre.com>
> ---
> v4 changes:
> - Fix typo s/get/set/ in commit message
> - Zero-initialize the bitmap to avoid compiler warning
> ---
>  drivers/bus/ts-nbus.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bus/ts-nbus.c b/drivers/bus/ts-nbus.c
> index b4c9308caf0647a3261071d9527fffce77784af2..17540034e64a4e591ea61b0b4eef86a2081b02f5 100644
> --- a/drivers/bus/ts-nbus.c
> +++ b/drivers/bus/ts-nbus.c
> @@ -10,6 +10,7 @@
>   * TS-4600 SoM.
>   */
>  
> +#include <linux/bitmap.h>
>  #include <linux/bitops.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/kernel.h>
> @@ -105,9 +106,9 @@ static void ts_nbus_set_direction(struct ts_nbus *ts_nbus, int direction)
>   */
>  static void ts_nbus_reset_bus(struct ts_nbus *ts_nbus)
>  {
> -	DECLARE_BITMAP(values, 8);
> +	DECLARE_BITMAP(values, 8) = { };
>  
> -	values[0] = 0;
> +	bitmap_set_value8(values, byte, 0);

I got distracted by an appointment and forgot to compile test before
sending. :-(

byte is undefined here. Will send v5 soon.

>  
>  	gpiod_multi_set_value_cansleep(ts_nbus->data, values);
>  	gpiod_set_value_cansleep(ts_nbus->csn, 0);
> @@ -149,9 +150,9 @@ static int ts_nbus_read_byte(struct ts_nbus *ts_nbus, u8 *val)
>   */
>  static void ts_nbus_write_byte(struct ts_nbus *ts_nbus, u8 byte)
>  {
> -	DECLARE_BITMAP(values, 8);
> +	DECLARE_BITMAP(values, 8) = { };
>  
> -	values[0] = byte;
> +	bitmap_set_value8(values, byte, 8);
>  
>  	gpiod_multi_set_value_cansleep(ts_nbus->data, values);
>  }
>