linux-kernel - Re: [PATCH] i2c: exynos5: Describe the hardware variant for readability

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Date:   Thu, 19 Jul 2018 14:35:18 +0900
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Andi Shyti <andi@...zian.org>, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: exynos5: Describe the hardware variant for
 readability

On 19-Jul-18 04:54, Krzysztof Kozlowski wrote:

> The driver supports multiple hardware variants of Exynos I2C controller
> which differ in FIFO depth, handling of interrupts and bus recovery in
> HSI2C_MASTER_ST_LOSE state.
>
> The difference in variant was a single bit set for Exynos7 variants and
> implicit lack of this bit for other variants.
>
> Make each variant explicit which also fixes the GCC warning about
> documentation:
>
>      drivers/i2c/busses/i2c-exynos5.c:223: warning: Function parameter or member 'hw' not described in 'exynos_hsi2c_variant'
>
> No change in functionality.
>
> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>

Maybe changing it to "bool is_exynos7" or sth like that would make it 
little more readable, matter of taste. Anyway:

Reviewed-by: Andrzej Hajda <a.hajda@...sung.com>

Regards
Andrzej
> ---
>   drivers/i2c/busses/i2c-exynos5.c | 22 ++++++++++++++--------
>   1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
> index de82ad8ff534..c1ce2299a76e 100644
> --- a/drivers/i2c/busses/i2c-exynos5.c
> +++ b/drivers/i2c/busses/i2c-exynos5.c
> @@ -176,7 +176,10 @@
>   
>   #define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(100))
>   
> -#define HSI2C_EXYNOS7	BIT(0)
> +enum i2c_type_exynos {
> +	I2C_TYPE_EXYNOS5,
> +	I2C_TYPE_EXYNOS7,
> +};
>   
>   struct exynos5_i2c {
>   	struct i2c_adapter	adap;
> @@ -212,27 +215,30 @@ struct exynos5_i2c {
>   /**
>    * struct exynos_hsi2c_variant - platform specific HSI2C driver data
>    * @fifo_depth: the fifo depth supported by the HSI2C module
> + * @hw: the hardware variant of Exynos I2C controller
>    *
>    * Specifies platform specific configuration of HSI2C module.
>    * Note: A structure for driver specific platform data is used for future
>    * expansion of its usage.
>    */
>   struct exynos_hsi2c_variant {
> -	unsigned int	fifo_depth;
> -	unsigned int	hw;
> +	unsigned int		fifo_depth;
> +	enum i2c_type_exynos	hw;
>   };
>   
>   static const struct exynos_hsi2c_variant exynos5250_hsi2c_data = {
>   	.fifo_depth	= 64,
> +	.hw		= I2C_TYPE_EXYNOS5,
>   };
>   
>   static const struct exynos_hsi2c_variant exynos5260_hsi2c_data = {
>   	.fifo_depth	= 16,
> +	.hw		= I2C_TYPE_EXYNOS5,
>   };
>   
>   static const struct exynos_hsi2c_variant exynos7_hsi2c_data = {
>   	.fifo_depth	= 16,
> -	.hw		= HSI2C_EXYNOS7,
> +	.hw		= I2C_TYPE_EXYNOS7,
>   };
>   
>   static const struct of_device_id exynos5_i2c_match[] = {
> @@ -300,7 +306,7 @@ static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, bool hs_timings)
>   	 */
>   	t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
>   	temp = clkin / op_clk - 8 - t_ftl_cycle;
> -	if (i2c->variant->hw != HSI2C_EXYNOS7)
> +	if (i2c->variant->hw != I2C_TYPE_EXYNOS7)
>   		temp -= t_ftl_cycle;
>   	div = temp / 512;
>   	clk_cycle = temp / (div + 1) - 2;
> @@ -424,7 +430,7 @@ static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
>   	writel(int_status, i2c->regs + HSI2C_INT_STATUS);
>   
>   	/* handle interrupt related to the transfer status */
> -	if (i2c->variant->hw == HSI2C_EXYNOS7) {
> +	if (i2c->variant->hw == I2C_TYPE_EXYNOS7) {
>   		if (int_status & HSI2C_INT_TRANS_DONE) {
>   			i2c->trans_done = 1;
>   			i2c->state = 0;
> @@ -571,7 +577,7 @@ static void exynos5_i2c_bus_check(struct exynos5_i2c *i2c)
>   {
>   	unsigned long timeout;
>   
> -	if (i2c->variant->hw != HSI2C_EXYNOS7)
> +	if (i2c->variant->hw != I2C_TYPE_EXYNOS7)
>   		return;
>   
>   	/*
> @@ -612,7 +618,7 @@ static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
>   	unsigned long flags;
>   	unsigned short trig_lvl;
>   
> -	if (i2c->variant->hw == HSI2C_EXYNOS7)
> +	if (i2c->variant->hw == I2C_TYPE_EXYNOS7)
>   		int_en |= HSI2C_INT_I2C_TRANS;
>   	else
>   		int_en |= HSI2C_INT_I2C;