Re: [PATCH v2 05/10] i2c: meson: set clock divider in probe instead of setting it for each transfer

[Heiner Kallweit <hkallweit1@gmail.com>]

Am 11.03.2017 um 00:17 schrieb Kevin Hilman:
> Heiner Kallweit <hkallweit1@gmail.com> writes:
> 
>> The bus frequency won't change, therefore we can set the clock divider
>> in probe already and we don't have to set it for each transfer.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> v2:
>> - no changes
>> ---
>>  drivers/i2c/busses/i2c-meson.c | 14 +++++++-------
>>  1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
>> index a5764be5..594fec22 100644
>> --- a/drivers/i2c/busses/i2c-meson.c
>> +++ b/drivers/i2c/busses/i2c-meson.c
>> @@ -74,7 +74,6 @@ enum {
>>   * @error:	Flag set when an error is received
>>   * @lock:	To avoid race conditions between irq handler and xfer code
>>   * @done:	Completion used to wait for transfer termination
>> - * @timings:	Struct including the bus frequency
> 
> You just added this field in PATCH 03/10.  Why not do this patch
> first, which will simplify the other.
> 
Yes, most likely this would be better. Will keep this in mind for the
upcoming v3.

> Kevin
> 
>>   * @tokens:	Sequence of tokens to be written to the device
>>   * @num_tokens:	Number of tokens
>>   */
>> @@ -93,7 +92,6 @@ struct meson_i2c {
>>  
>>  	spinlock_t		lock;
>>  	struct completion	done;
>> -	struct i2c_timings	timings;
>>  	u32			tokens[2];
>>  	int			num_tokens;
>>  };
>> @@ -132,12 +130,12 @@ static void meson_i2c_write_tokens(struct meson_i2c *i2c)
>>  	writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
>>  }
>>  
>> -static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
>> +static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
>>  {
>>  	unsigned long clk_rate = clk_get_rate(i2c->clk);
>>  	unsigned int div;
>>  
>> -	div = DIV_ROUND_UP(clk_rate, i2c->timings.bus_freq_hz * 4);
>> +	div = DIV_ROUND_UP(clk_rate, freq * 4);
>>  
>>  	/* clock divider has 12 bits */
>>  	WARN_ON(div >= (1 << 12));
>> @@ -149,7 +147,7 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
>>  			   (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
>>  
>>  	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
>> -		clk_rate, i2c->timings.bus_freq_hz, div);
>> +		clk_rate, freq, div);
>>  }
>>  
>>  static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
>> @@ -369,7 +367,6 @@ static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>  	int i, ret = 0, count = 0;
>>  
>>  	clk_enable(i2c->clk);
>> -	meson_i2c_set_clk_div(i2c);
>>  
>>  	for (i = 0; i < num; i++) {
>>  		ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
>> @@ -396,6 +393,7 @@ static const struct i2c_algorithm meson_i2c_algorithm = {
>>  static int meson_i2c_probe(struct platform_device *pdev)
>>  {
>>  	struct device_node *np = pdev->dev.of_node;
>> +	struct i2c_timings timings;
>>  	struct meson_i2c *i2c;
>>  	struct resource *mem;
>>  	int irq, ret = 0;
>> @@ -404,7 +402,7 @@ static int meson_i2c_probe(struct platform_device *pdev)
>>  	if (!i2c)
>>  		return -ENOMEM;
>>  
>> -	i2c_parse_fw_timings(&pdev->dev, &i2c->timings, true);
>> +	i2c_parse_fw_timings(&pdev->dev, &timings, true);
>>  
>>  	i2c->dev = &pdev->dev;
>>  	platform_set_drvdata(pdev, i2c);
>> @@ -462,6 +460,8 @@ static int meson_i2c_probe(struct platform_device *pdev)
>>  		return ret;
>>  	}
>>  
>> +	meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
>> +
>>  	return 0;
>>  }
>