5 Aug
2009
5 Aug
'09
10:42 a.m.
On Wed, 5 Aug 2009 10:21:49 +0300 Jarkko Nikula jhnikula@gmail.com wrote:
If my analysis is correct, the best solution I can see would be starting McBSP transfer for one direction only, not both, so the opposite direction can be started when needed. That requires deeper and wider OMAP knowledge and a change in omap_mcbsp_start() API though. I am not in a position to deal with this myself, I'm afraid.
I favor this change. Actually I remember I was thinking shortly to change API of omap_mcbsp_start and _stop more than year back or so but didn't find it necessary back then.
I think change will be trivial. Basically two new arguments indicating are the TX/RX active and let the first/last caller to deal with sample-rate generator and frame sync activation/de-activation.
I hacked a patch below. Can you test does it help?
--
Jarkko
---
diff --git a/arch/arm/plat-omap/include/mach/mcbsp.h b/arch/arm/plat-omap/include/mach/mcbsp.h
index bb154ea..57249bb 100644
--- a/arch/arm/plat-omap/include/mach/mcbsp.h
+++ b/arch/arm/plat-omap/include/mach/mcbsp.h
@@ -387,8 +387,8 @@ void omap_mcbsp_register_board_cfg(struct omap_mcbsp_platform_data *config,
void omap_mcbsp_config(unsigned int id, const struct omap_mcbsp_reg_cfg * config);
int omap_mcbsp_request(unsigned int id);
void omap_mcbsp_free(unsigned int id);
-void omap_mcbsp_start(unsigned int id);
-void omap_mcbsp_stop(unsigned int id);
+void omap_mcbsp_start(unsigned int id, int tx, int rx);
+void omap_mcbsp_stop(unsigned int id, int tx, int rx);
void omap_mcbsp_xmit_word(unsigned int id, u32 word);
u32 omap_mcbsp_recv_word(unsigned int id);
diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c
index efa0e01..d7645b3 100644
--- a/arch/arm/plat-omap/mcbsp.c
+++ b/arch/arm/plat-omap/mcbsp.c
@@ -328,14 +328,15 @@ void omap_mcbsp_free(unsigned int id)
EXPORT_SYMBOL(omap_mcbsp_free);
/*
- * Here we start the McBSP, by enabling the sample
- * generator, both transmitter and receivers,
- * and the frame sync.
+ * Here we start the McBSP, by enabling transmitter, receiver or both.
+ * If no transmitter or receiver is active prior calling, then sample-rate
+ * generator and frame sync are started.
*/
-void omap_mcbsp_start(unsigned int id)
+void omap_mcbsp_start(unsigned int id, int tx, int rx)
{
struct omap_mcbsp *mcbsp;
void __iomem *io_base;
+ int idle;
u16 w;
if (!omap_mcbsp_check_valid_id(id)) {
@@ -348,32 +349,40 @@ void omap_mcbsp_start(unsigned int id)
mcbsp->rx_word_length = (OMAP_MCBSP_READ(io_base, RCR1) >> 5) & 0x7;
mcbsp->tx_word_length = (OMAP_MCBSP_READ(io_base, XCR1) >> 5) & 0x7;
- /* Start the sample generator */
- w = OMAP_MCBSP_READ(io_base, SPCR2);
- OMAP_MCBSP_WRITE(io_base, SPCR2, w | (1 << 6));
+ idle = !((OMAP_MCBSP_READ(io_base, SPCR2) |
+ OMAP_MCBSP_READ(io_base, SPCR1)) & 1);
+
+ if (idle) {
+ /* Start the sample generator */
+ w = OMAP_MCBSP_READ(io_base, SPCR2);
+ OMAP_MCBSP_WRITE(io_base, SPCR2, w | (1 << 6));
+ }
/* Enable transmitter and receiver */
w = OMAP_MCBSP_READ(io_base, SPCR2);
- OMAP_MCBSP_WRITE(io_base, SPCR2, w | 1);
+ OMAP_MCBSP_WRITE(io_base, SPCR2, w | (tx & 1));
w = OMAP_MCBSP_READ(io_base, SPCR1);
- OMAP_MCBSP_WRITE(io_base, SPCR1, w | 1);
+ OMAP_MCBSP_WRITE(io_base, SPCR1, w | (rx & 1));
udelay(100);
- /* Start frame sync */
- w = OMAP_MCBSP_READ(io_base, SPCR2);
- OMAP_MCBSP_WRITE(io_base, SPCR2, w | (1 << 7));
+ if (idle) {
+ /* Start frame sync */
+ w = OMAP_MCBSP_READ(io_base, SPCR2);
+ OMAP_MCBSP_WRITE(io_base, SPCR2, w | (1 << 7));
+ }
/* Dump McBSP Regs */
omap_mcbsp_dump_reg(id);
}
EXPORT_SYMBOL(omap_mcbsp_start);
-void omap_mcbsp_stop(unsigned int id)
+void omap_mcbsp_stop(unsigned int id, int tx, int rx)
{
struct omap_mcbsp *mcbsp;
void __iomem *io_base;
+ int idle;
u16 w;
if (!omap_mcbsp_check_valid_id(id)) {
@@ -386,15 +395,20 @@ void omap_mcbsp_stop(unsigned int id)
/* Reset transmitter */
w = OMAP_MCBSP_READ(io_base, SPCR2);
- OMAP_MCBSP_WRITE(io_base, SPCR2, w & ~(1));
+ OMAP_MCBSP_WRITE(io_base, SPCR2, w & ~(tx & 1));
/* Reset receiver */
w = OMAP_MCBSP_READ(io_base, SPCR1);
- OMAP_MCBSP_WRITE(io_base, SPCR1, w & ~(1));
+ OMAP_MCBSP_WRITE(io_base, SPCR1, w & ~(rx & 1));
- /* Reset the sample rate generator */
- w = OMAP_MCBSP_READ(io_base, SPCR2);
- OMAP_MCBSP_WRITE(io_base, SPCR2, w & ~(1 << 6));
+ idle = !((OMAP_MCBSP_READ(io_base, SPCR2) |
+ OMAP_MCBSP_READ(io_base, SPCR1)) & 1);
+
+ if (idle) {
+ /* Reset the sample rate generator */
+ w = OMAP_MCBSP_READ(io_base, SPCR2);
+ OMAP_MCBSP_WRITE(io_base, SPCR2, w & ~(1 << 6));
+ }
}
EXPORT_SYMBOL(omap_mcbsp_stop);
diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
index a5d46a7..9368bca 100644
--- a/sound/soc/omap/omap-mcbsp.c
+++ b/sound/soc/omap/omap-mcbsp.c
@@ -183,21 +183,21 @@ static int omap_mcbsp_dai_trigger(struct snd_pcm_substream *substream, int cmd,
struct snd_soc_pcm_runtime *rtd = substream->private_data;
struct snd_soc_dai *cpu_dai = rtd->dai->cpu_dai;
struct omap_mcbsp_data *mcbsp_data = to_mcbsp(cpu_dai->private_data);
- int err = 0;
+ int err = 0, play = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
- if (!mcbsp_data->active++)
- omap_mcbsp_start(mcbsp_data->bus_id);
+ mcbsp_data->active++;
+ omap_mcbsp_start(mcbsp_data->bus_id, play, !play);
break;
case SNDRV_PCM_TRIGGER_STOP:
case SNDRV_PCM_TRIGGER_SUSPEND:
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
- if (!--mcbsp_data->active)
- omap_mcbsp_stop(mcbsp_data->bus_id);
+ mcbsp_data->active--;
+ omap_mcbsp_stop(mcbsp_data->bus_id, play, !play);
break;
default:
err = -EINVAL;