Re: [PATCH 4/4] iio: buffer: Coalesce adjacent demux table entries

[Jonathan Cameron <jic23@kernel.org>]

On 20/07/14 16:14, Jonathan Cameron wrote:
> On 17/07/14 16:59, Lars-Peter Clausen wrote:
>> When copying multiple multiple samples that are adjacent in both the source as
>> well as the destination buffer, instead of creating a new demux table entry for
>> each sample just increase the length of the previous entry by the size of the
>> new sample. This makes the demuxing process slightly more efficient.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> Nice.  Will hold these last two until the first one is in and we have decided
> what to do about the second one.
Applied to the togreg branch of iio.git.

Given Linus' comments on the last rc, there is unlikely to be another IIO pull
request until after the merge window.

Jonathan
>
> J
>> ---
>>   drivers/iio/industrialio-buffer.c | 47 +++++++++++++++++++++++----------------
>>   1 file changed, 28 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
>> index 5063703..779e5b3 100644
>> --- a/drivers/iio/industrialio-buffer.c
>> +++ b/drivers/iio/industrialio-buffer.c
>> @@ -942,13 +942,34 @@ int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
>>   }
>>   EXPORT_SYMBOL_GPL(iio_push_to_buffers);
>>
>> +static int iio_buffer_add_demux(struct iio_buffer *buffer,
>> +    struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
>> +    unsigned int length)
>> +{
>> +
>> +    if (*p && (*p)->from + (*p)->length == in_loc &&
>> +        (*p)->to + (*p)->length == out_loc) {
>> +        (*p)->length += length;
>> +    } else {
>> +        *p = kmalloc(sizeof(*p), GFP_KERNEL);
>> +        if (*p == NULL)
>> +            return -ENOMEM;
>> +        (*p)->from = in_loc;
>> +        (*p)->to = out_loc;
>> +        (*p)->length = length;
>> +        list_add_tail(&(*p)->l, &buffer->demux_list);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>   static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>>                      struct iio_buffer *buffer)
>>   {
>>       const struct iio_chan_spec *ch;
>>       int ret, in_ind = -1, out_ind, length;
>>       unsigned in_loc = 0, out_loc = 0;
>> -    struct iio_demux_table *p;
>> +    struct iio_demux_table *p = NULL;
>>
>>       /* Clear out any old demux */
>>       iio_buffer_demux_free(buffer);
>> @@ -981,11 +1002,6 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>>               /* Make sure we are aligned */
>>               in_loc = roundup(in_loc, length) + length;
>>           }
>> -        p = kmalloc(sizeof(*p), GFP_KERNEL);
>> -        if (p == NULL) {
>> -            ret = -ENOMEM;
>> -            goto error_clear_mux_table;
>> -        }
>>           ch = iio_find_channel_from_si(indio_dev, in_ind);
>>           if (ch->scan_type.repeat > 1)
>>               length = ch->scan_type.storagebits / 8 *
>> @@ -994,20 +1010,14 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>>               length = ch->scan_type.storagebits / 8;
>>           out_loc = roundup(out_loc, length);
>>           in_loc = roundup(in_loc, length);
>> -        p->from = in_loc;
>> -        p->to = out_loc;
>> -        p->length = length;
>> -        list_add_tail(&p->l, &buffer->demux_list);
>> +        ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
>> +        if (ret)
>> +            goto error_clear_mux_table;
>>           out_loc += length;
>>           in_loc += length;
>>       }
>>       /* Relies on scan_timestamp being last */
>>       if (buffer->scan_timestamp) {
>> -        p = kmalloc(sizeof(*p), GFP_KERNEL);
>> -        if (p == NULL) {
>> -            ret = -ENOMEM;
>> -            goto error_clear_mux_table;
>> -        }
>>           ch = iio_find_channel_from_si(indio_dev,
>>               indio_dev->scan_index_timestamp);
>>           if (ch->scan_type.repeat > 1)
>> @@ -1017,10 +1027,9 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev,
>>               length = ch->scan_type.storagebits / 8;
>>           out_loc = roundup(out_loc, length);
>>           in_loc = roundup(in_loc, length);
>> -        p->from = in_loc;
>> -        p->to = out_loc;
>> -        p->length = length;
>> -        list_add_tail(&p->l, &buffer->demux_list);
>> +        ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
>> +        if (ret)
>> +            goto error_clear_mux_table;
>>           out_loc += length;
>>           in_loc += length;
>>       }
>>
>
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