Re: [PATCH 2/2] iio: imu: inv_mpu6050: make loop a do-while - Jean-Baptiste Maneyrol

From: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
To: Jonathan Cameron <jic23@jic23.retrosnub.co.uk>,
	Martin Kelly <mkelly@xevo.com>
Cc: linux-iio@vger.kernel.org
Subject: Re: [PATCH 2/2] iio: imu: inv_mpu6050: make loop a do-while
Date: Tue, 8 May 2018 16:34:30 +0200	[thread overview]
Message-ID: <f618c12b-2d79-c6e3-abfa-8c377f07640d@invensense.com> (raw)
In-Reply-To: <20180506180816.4c15b826@archlinux>

On 06/05/2018 19:08, Jonathan Cameron wrote:
> On Tue,  1 May 2018 10:56:42 -0700
> Martin Kelly <mkelly@xevo.com> wrote:
> 
>> Prior to this loop, we check if fifo_count < bytes_per_datum and bail if
>> so. This means that when we hit the loop, we know that fifo_count >=
>> bytes_per_datum, so the check is unneeded and we can turn the loop into
>> a do-while for a slight performance improvement.
>>
>> Signed-off-by: Martin Kelly <mkelly@xevo.com>
> Seems logical to me, but I'd like to give Jean-Baptiste a chance
> to comment on this one.
> 
> If it looks like we have forgotten about it in a week or so do
> give me a poke!
> 
> Thanks,
> 
> Jonathan
Hello,

no problem for me, looks good. Anyway, I'm planning additionnal changes 
that are going to change completely this loop.

JB
> 
>> ---
>>   drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
>> index 0cb7c20100ca..11593deaaebd 100644
>> --- a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
>> +++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
>> @@ -174,7 +174,7 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
>>   	if (kfifo_len(&st->timestamps) >
>>   	    fifo_count / bytes_per_datum + INV_MPU6050_TIME_STAMP_TOR)
>>   		goto flush_fifo;
>> -	while (fifo_count >= bytes_per_datum) {
>> +	do {
>>   		result = regmap_bulk_read(st->map, st->reg->fifo_r_w,
>>   					  data, bytes_per_datum);
>>   		if (result)
>> @@ -188,7 +188,7 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
>>   		iio_push_to_buffers_with_timestamp(indio_dev, data, timestamp);
>>   
>>   		fifo_count -= bytes_per_datum;
>> -	}
>> +	} while (fifo_count >= bytes_per_datum);
>>   
>>   end_session:
>>   	mutex_unlock(&st->lock);
> 
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