[Sound-open-firmware] [PATCH] dma-trace: Fix reschedule bug to avoid dma buffer overflow

[Xiuli Pan]

From: Pan Xiuli <xiuli.pan at linux.intel.com>

We have wrong logic in reschedule, we always reschedule the trace_work
once the buffer is half full and new trace coming. We will delay the old
schedule before the old scheduled trace_work is finally run.
Thus the trace_work will like the carrot in front of the DSP as the donkey,
the DSP will never run the trace_work that scheduled in the furture
while we are in busy state and lots of trace are coming continuously.

Signed-off-by: Pan Xiuli <xiuli.pan at linux.intel.com>
Reviewed-by: Zhigang Wu <zhigang.wu at linux.intel.com>
Tested-by: Zhigang Wu <zhigang.wu at linux.intel.com>

---
Test with:
Mininow max rt5651 and GP-MRB nocodec and CNL nocodec
SOF 1.1-stable: 210989dffeea811de2370fccb7cf5d53106b1e6e
SOF-Tool 1.1-stable: 49c1b450e635ac0c893d67ff0ddfd34e03a85b46
https://github.com/plbossart/sound/tree/topic/sof-v4.14:
8d8c1bb32537800726b14d00d13f324b7f536386
---
 src/include/reef/dma-trace.h | 1 +
 src/lib/dma-trace.c          | 9 ++++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/include/reef/dma-trace.h b/src/include/reef/dma-trace.h
index f17ffe5..5ef5eb2 100644
--- a/src/include/reef/dma-trace.h
+++ b/src/include/reef/dma-trace.h
@@ -63,6 +63,7 @@ struct dma_trace_data {
 	struct work dmat_work;
 	uint32_t enabled;
 	uint32_t copy_in_progress;
+	uint32_t rescheduled;
 	uint32_t stream_tag;
 	spinlock_t lock;
 };
diff --git a/src/lib/dma-trace.c b/src/lib/dma-trace.c
index 1ff2bd4..ef29026 100644
--- a/src/lib/dma-trace.c
+++ b/src/lib/dma-trace.c
@@ -128,6 +128,9 @@ out:
 	ipc_dma_trace_send_position();
 #endif
 
+	/* enable reschedule after one copy is done */
+	if (d->rescheduled)
+		d->rescheduled = 0;
 	/* reschedule the trace copying work */
 	return DMA_TRACE_PERIOD;
 }
@@ -137,6 +140,7 @@ int dma_trace_init_early(struct reef *reef)
 	struct dma_trace_buf *buffer;
 
 	trace_data = rzalloc(RZONE_SYS, SOF_MEM_CAPS_RAM, sizeof(*trace_data));
+	trace_data->rescheduled = 0;
 	buffer = &trace_data->dmatb;
 
 	/* allocate new buffer */
@@ -335,9 +339,12 @@ void dtrace_event(const char *e, uint32_t length)
 	spin_unlock_irq(&trace_data->lock, flags);
 
 	/* schedule copy now if buffer > 50% full */
-	if (trace_data->enabled && buffer->avail >= (DMA_TRACE_LOCAL_SIZE / 2))
+	if (trace_data->enabled && !trace_data->rescheduled &&
+	    buffer->avail >= (DMA_TRACE_LOCAL_SIZE / 2)) {
 		work_reschedule_default(&trace_data->dmat_work,
 		DMA_TRACE_RESCHEDULE_TIME);
+		trace_data->rescheduled = 1;
+	}
 }
 
 void dtrace_event_atomic(const char *e, uint32_t length)
-- 
2.7.4