Re: [PATCH v7 06/34] i2c: tegra: Remove i2c_dev.clk_divisor_non_hs_mode member

Dmitry Osipenko
2020-09-17T15:31:54Z

17.09.2020 14:25, Thierry Reding пишет:
> 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@rere.qmqm.pl>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.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.

The reason is make it readable :) For me it's too difficult to read > <=
&& { } + no proper indentation.

The switches are more suitable for ranges, IMO. Especially when there
are multiple ranges, and there could be more ranges in the future in
this code.