linux-kernel - Re: [PATCH v3] i2c: busses: Use min() to improve code

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Message-ID: <20250708120658.0000668a@huawei.com>
Date: Tue, 8 Jul 2025 12:06:58 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Qianfeng Rong <rongqianfeng@...o.com>
CC: <wsa+renesas@...g-engineering.com>, Patrice Chotard
	<patrice.chotard@...s.st.com>, Andi Shyti <andi.shyti@...nel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-i2c@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <opensource.kernel@...o.com>
Subject: Re: [PATCH v3] i2c: busses: Use min() to improve code

On Tue,  8 Jul 2025 11:15:20 +0800
Qianfeng Rong <rongqianfeng@...o.com> wrote:

> Use min() to reduce the code and improve its readability.
> 
> The type of the max parameter in the st_i2c_rd_fill_tx_fifo()
> was changed from int to u32, because the max parameter passed
> in is always greater than 0.
> 
> Signed-off-by: Qianfeng Rong <rongqianfeng@...o.com>
> Reviewed-by: Patrice Chotard <patrice.chotard@...s.st.com>
> ---
> v2-> v3:
> - added the <linux/minmax.h> as suggested by Jonathan.
> - used i = min(...) as the loop initializer according
>   to Jonathan.
> 
> v1-> v2:
> - Change the max parameter type in st_i2c_rd_fill_tx_fifo()
>   from int to u32
> ---
>  drivers/i2c/busses/i2c-st.c | 19 ++++++-------------
>  1 file changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c
> index 750fff3d2389..e4b2ed8a9264 100644
> --- a/drivers/i2c/busses/i2c-st.c
> +++ b/drivers/i2c/busses/i2c-st.c
> @@ -19,6 +19,7 @@
>  #include <linux/of.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
> +#include <linux/minmax.h>
>  
>  /* SSC registers */
>  #define SSC_BRG				0x000
> @@ -422,12 +423,8 @@ static void st_i2c_wr_fill_tx_fifo(struct st_i2c_dev *i2c_dev)
>  	tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
>  	tx_fstat &= SSC_TX_FSTAT_STATUS;
>  
> -	if (c->count < (SSC_TXFIFO_SIZE - tx_fstat))
> -		i = c->count;
> -	else
> -		i = SSC_TXFIFO_SIZE - tx_fstat;
> -
> -	for (; i > 0; i--, c->count--, c->buf++)
> +	for (i = min(c->count, SSC_TXFIFO_SIZE - tx_fstat);
> +		i > 0; i--, c->count--, c->buf++)
	for (i = min(c->count, SSC_TXFIFO_SIZE - tx_fstat);
	     i > 0; i--, c->count--, c->buf++)
  		st_i2c_write_tx_fifo(i2c_dev, *c->buf);

So different alignment form what you have.


>  		st_i2c_write_tx_fifo(i2c_dev, *c->buf);
>  }
>  
> @@ -439,7 +436,7 @@ static void st_i2c_wr_fill_tx_fifo(struct st_i2c_dev *i2c_dev)
>   * This functions fills the Tx FIFO with fixed pattern when
>   * in read mode to trigger clock.
>   */
> -static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, int max)
> +static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, u32 max)
>  {
>  	struct st_i2c_client *c = &i2c_dev->client;
>  	u32 tx_fstat, sta;
> @@ -452,12 +449,8 @@ static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, int max)
>  	tx_fstat = readl_relaxed(i2c_dev->base + SSC_TX_FSTAT);
>  	tx_fstat &= SSC_TX_FSTAT_STATUS;
>  
> -	if (max < (SSC_TXFIFO_SIZE - tx_fstat))
> -		i = max;
> -	else
> -		i = SSC_TXFIFO_SIZE - tx_fstat;
> -
> -	for (; i > 0; i--, c->xfered++)
> +	for (i = min(max, SSC_TXFIFO_SIZE - tx_fstat);
> +		i > 0; i--, c->xfered++)
>  		st_i2c_write_tx_fifo(i2c_dev, 0xff);
>  }
>