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ALSA: firewire-lib: code refactoring for syt offset calculation 

When calculating syt offset, some states are stored in AMDTP stream
structure. This is inconvenient when reuse the calculation from
non-stream structure.

This commit applies refactoring to helper function for the calculation
so that the function doesn't touch AMDTP stream structure.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200508043635.349339-7-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Sakamoto 2020-05-08 13:36:31 +09:00 committed by Takashi Iwai
parent 83cfb5c50f
commit 816d84826e
1 changed files with 16 additions and 13 deletions
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29
sound/firewire/amdtp-stream.c
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@ -383,14 +383,14 @@ static unsigned int calculate_data_blocks(struct amdtp_stream *s,
return data_blocks;
}
static unsigned int calculate_syt_offset(struct amdtp_stream *s)
static unsigned int calculate_syt_offset(unsigned int *last_syt_offset,
unsigned int *syt_offset_state, enum cip_sfc sfc)
{
unsigned int syt_offset, phase, index;
unsigned int syt_offset;
if (s->ctx_data.rx.last_syt_offset < TICKS_PER_CYCLE) {
if (!cip_sfc_is_base_44100(s->sfc))
syt_offset = s->ctx_data.rx.last_syt_offset +
s->ctx_data.rx.syt_offset_state;
if (*last_syt_offset < TICKS_PER_CYCLE) {
if (!cip_sfc_is_base_44100(sfc))
syt_offset = *last_syt_offset + *syt_offset_state;
else {
/*
* The time, in ticks, of the n'th SYT_INTERVAL sample is:
@ -402,18 +402,19 @@ static unsigned int calculate_syt_offset(struct amdtp_stream *s)
* 1386 1386 1387 1386 1386 1386 1387 1386 1386 1386 1387 ...
* This code generates _exactly_ the same sequence.
*/
phase = s->ctx_data.rx.syt_offset_state;
index = phase % 13;
syt_offset = s->ctx_data.rx.last_syt_offset;
unsigned int phase = *syt_offset_state;
unsigned int index = phase % 13;
syt_offset = *last_syt_offset;
syt_offset += 1386 + ((index && !(index & 3)) ||
phase == 146);
if (++phase >= 147)
phase = 0;
s->ctx_data.rx.syt_offset_state = phase;
*syt_offset_state = phase;
}
} else
syt_offset = s->ctx_data.rx.last_syt_offset - TICKS_PER_CYCLE;
s->ctx_data.rx.last_syt_offset = syt_offset;
syt_offset = *last_syt_offset - TICKS_PER_CYCLE;
*last_syt_offset = syt_offset;
if (syt_offset >= TICKS_PER_CYCLE)
syt_offset = CIP_SYT_NO_INFO;
@ -759,7 +760,9 @@ static void generate_ideal_pkt_descs(struct amdtp_stream *s,
unsigned int syt_offset;
desc->cycle = compute_it_cycle(*ctx_header, s->queue_size);
syt_offset = calculate_syt_offset(s);
syt_offset = calculate_syt_offset(
&s->ctx_data.rx.last_syt_offset,
&s->ctx_data.rx.syt_offset_state, s->sfc);
if (syt_offset != CIP_SYT_NO_INFO) {
desc->syt = compute_syt(syt_offset, desc->cycle,
s->ctx_data.rx.transfer_delay);