linux-kernel - Re: [PATCH 09/10] iio: imu: kmx61: Drop odr_bits from kmx61_samp_freq

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Date:	Sun, 04 Jan 2015 10:55:35 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Hartmut Knaack <knaack.h@....de>,
	Daniel Baluta <daniel.baluta@...el.com>
CC:	lars@...afoo.de, pmeerw@...erw.net, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, srinivas.pandruvada@...ux.intel.com
Subject: Re: [PATCH 09/10] iio: imu: kmx61: Drop odr_bits from kmx61_samp_freq_table

On 01/01/15 13:53, Hartmut Knaack wrote:
> Daniel Baluta schrieb am 23.12.2014 um 14:22:
>> odr_bits values are between 0 and 11, so we can use the index
>> in kmx61_samp_freq_table instead of odr_bits structure member.
> Basically looking good, but I would feel more comfortable to check
> against the boundaries of the table. Please see inline.
> 
>>
>> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
>> ---
>>  drivers/iio/imu/kmx61.c | 64 ++++++++++++++++++++-----------------------------
>>  1 file changed, 26 insertions(+), 38 deletions(-)
>>
>> diff --git a/drivers/iio/imu/kmx61.c b/drivers/iio/imu/kmx61.c
>> index eb3900e..98369eb 100644
>> --- a/drivers/iio/imu/kmx61.c
>> +++ b/drivers/iio/imu/kmx61.c
>> @@ -169,19 +169,18 @@ u16 kmx61_uscale_table[] = {9582, 19163, 38326};
>>  static const struct {
>>  	int val;
>>  	int val2;
>> -	u8 odr_bits;
>> -} kmx61_samp_freq_table[] = { {12, 500000, 0x00},
>> -			{25, 0, 0x01},
>> -			{50, 0, 0x02},
>> -			{100, 0, 0x03},
>> -			{200, 0, 0x04},
>> -			{400, 0, 0x05},
>> -			{800, 0, 0x06},
>> -			{1600, 0, 0x07},
>> -			{0, 781000, 0x08},
>> -			{1, 563000, 0x09},
>> -			{3, 125000, 0x0A},
>> -			{6, 250000, 0x0B} };
>> +} kmx61_samp_freq_table[] = { {12, 500000},
>> +			{25, 0},
>> +			{50, 0},
>> +			{100, 0},
>> +			{200, 0},
>> +			{400, 0},
>> +			{800, 0},
>> +			{1600, 0},
>> +			{0, 781000},
>> +			{1, 563000},
>> +			{3, 125000},
>> +			{6, 250000} };
>>  
>>  static const struct {
>>  	int val;
>> @@ -302,24 +301,10 @@ static int kmx61_convert_freq_to_bit(int val, int val2)
>>  	for (i = 0; i < ARRAY_SIZE(kmx61_samp_freq_table); i++)
>>  		if (val == kmx61_samp_freq_table[i].val &&
>>  		    val2 == kmx61_samp_freq_table[i].val2)
>> -			return kmx61_samp_freq_table[i].odr_bits;
>> -	return -EINVAL;
>> -}
>> -
>> -static int kmx61_convert_bit_to_freq(u8 odr_bits, int *val, int *val2)
>> -{
>> -	int i;
>> -
>> -	for (i = 0; i < ARRAY_SIZE(kmx61_samp_freq_table); i++)
>> -		if (odr_bits == kmx61_samp_freq_table[i].odr_bits) {
>> -			*val = kmx61_samp_freq_table[i].val;
>> -			*val2 = kmx61_samp_freq_table[i].val2;
>> -			return 0;
>> -		}
>> +			return i;
>>  	return -EINVAL;
>>  }
>>  
>> -
>>  static int kmx61_convert_wake_up_odr_to_bit(int val, int val2)
>>  {
>>  	int i;
>> @@ -478,7 +463,7 @@ static int kmx61_set_odr(struct kmx61_data *data, int val, int val2, u8 device)
>>  
>>  static int kmx61_get_odr(struct kmx61_data *data, int *val, int *val2,
>>  			 u8 device)
>> -{	int i;
>> +{
>>  	u8 lodr_bits;
>>  
>>  	if (device & KMX61_ACC)
>> @@ -490,13 +475,13 @@ static int kmx61_get_odr(struct kmx61_data *data, int *val, int *val2,
>>  	else
>>  		return -EINVAL;
>>  
>> -	for (i = 0; i < ARRAY_SIZE(kmx61_samp_freq_table); i++)
>> -		if (lodr_bits == kmx61_samp_freq_table[i].odr_bits) {
>> -			*val = kmx61_samp_freq_table[i].val;
>> -			*val2 = kmx61_samp_freq_table[i].val2;
>> -			return 0;
>> -		}
>> -	return -EINVAL;
>> +	if (lodr_bits > 0xB)
> Since we use it as an index, I regard it safer to check against
> ARRAY_SIZE(kmx61_samp_freq_table) rather than a fix value.
Makes sense to me as well - though obviously ARRAY_SIZE(kmx61_samp_freq_table) is
0xC (12) rather than 0xB (11) so you'll need a minus 1

I'll leave this one for a new spin.
> 
>> +		return -EINVAL;
>> +
>> +	*val = kmx61_samp_freq_table[lodr_bits].val;
>> +	*val2 = kmx61_samp_freq_table[lodr_bits].val2;
>> +
>> +	return 0;
>>  }
>>  
>>  static int kmx61_set_range(struct kmx61_data *data, u8 range)
>> @@ -580,8 +565,11 @@ static int kmx61_chip_init(struct kmx61_data *data)
>>  	}
>>  	data->odr_bits = ret;
>>  
>> -	/* set output data rate for wake up (motion detection) function */
>> -	ret = kmx61_convert_bit_to_freq(data->odr_bits, &val, &val2);
>> +	/*
>> +	 * set output data rate for wake up (motion detection) function
>> +	 * to match data rate for accelerometer sampling
>> +	 */
>> +	ret = kmx61_get_odr(data, &val, &val2, KMX61_ACC);
>>  	if (ret < 0)
>>  		return ret;
>>  
>>
> 

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