linux-kernel - Re: [PATCH v7 06/34] i2c: tegra: Remove i2c_dev.clk_divisor_non_hs

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Message-ID: <20200917112541.GR3515672@ulmo>
Date:   Thu, 17 Sep 2020 13:25:41 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 06/34] i2c: tegra: Remove
 i2c_dev.clk_divisor_non_hs_mode member

On Wed, Sep 09, 2020 at 01:39:38AM +0300, Dmitry Osipenko wrote:
> The "non_hs_mode" divisor value is fixed, thus there is no need to have
> the variable i2c_dev.clk_divisor_non_hs_mode struct member. Let's remove
> it and move the mode selection into tegra_i2c_init() where it can be
> united with the timing selection.
> 
> Reviewed-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/i2c/busses/i2c-tegra.c | 46 ++++++++++++++++------------------
>  1 file changed, 21 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 720a75439e91..85ed0e02d48c 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -250,7 +250,6 @@ struct tegra_i2c_hw_feature {
>   * @msg_buf_remaining: size of unsent data in the message buffer
>   * @msg_read: identifies read transfers
>   * @bus_clk_rate: current I2C bus clock rate
> - * @clk_divisor_non_hs_mode: clock divider for non-high-speed modes
>   * @is_multimaster_mode: track if I2C controller is in multi-master mode
>   * @tx_dma_chan: DMA transmit channel
>   * @rx_dma_chan: DMA receive channel
> @@ -281,7 +280,6 @@ struct tegra_i2c_dev {
>  	size_t msg_buf_remaining;
>  	int msg_read;
>  	u32 bus_clk_rate;
> -	u16 clk_divisor_non_hs_mode;
>  	bool is_multimaster_mode;
>  	struct dma_chan *tx_dma_chan;
>  	struct dma_chan *rx_dma_chan;
> @@ -783,6 +781,7 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>  	u32 val;
>  	int err;
>  	u32 clk_divisor, clk_multiplier;
> +	u32 non_hs_mode;
>  	u32 tsu_thd;
>  	u8 tlow, thigh;
>  
> @@ -805,24 +804,33 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
>  	if (i2c_dev->is_vi)
>  		tegra_i2c_vi_init(i2c_dev);
>  
> -	/* Make sure clock divisor programmed correctly */
> -	clk_divisor = FIELD_PREP(I2C_CLK_DIVISOR_HSMODE,
> -				 i2c_dev->hw->clk_divisor_hs_mode) |
> -		      FIELD_PREP(I2C_CLK_DIVISOR_STD_FAST_MODE,
> -				 i2c_dev->clk_divisor_non_hs_mode);
> -	i2c_writel(i2c_dev, clk_divisor, I2C_CLK_DIVISOR);
> -
> -	if (i2c_dev->bus_clk_rate > I2C_MAX_STANDARD_MODE_FREQ &&
> -	    i2c_dev->bus_clk_rate <= I2C_MAX_FAST_MODE_PLUS_FREQ) {
> +	switch (i2c_dev->bus_clk_rate) {
> +	case I2C_MAX_STANDARD_MODE_FREQ + 1 ... I2C_MAX_FAST_MODE_PLUS_FREQ:

Is there are particular reason for switching the simple conditional to a
switch here? The old variant looks much easier to understand to me.

Thierry

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