[PATCH 3/4] media: stm32-dcmi: clarify state logic on buffer starvation

From: Hugues Fruchet
Date: Mon Jun 11 2018 - 05:51:52 EST


Introduce WAIT_FOR_BUFFER state instead of "active" field checking
to manage buffer starvation case.

Signed-off-by: Hugues Fruchet <hugues.fruchet@xxxxxx>
---
drivers/media/platform/stm32/stm32-dcmi.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
index 6ccf195..93bb03a 100644
--- a/drivers/media/platform/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/stm32/stm32-dcmi.c
@@ -85,6 +85,7 @@

enum state {
STOPPED = 0,
+ WAIT_FOR_BUFFER,
RUNNING,
STOPPING,
};
@@ -230,6 +231,7 @@ static int dcmi_restart_capture(struct stm32_dcmi *dcmi)
if (list_empty(&dcmi->buffers)) {
dev_dbg(dcmi->dev, "Capture restart is deferred to next buffer queueing\n");
dcmi->active = NULL;
+ dcmi->state = WAIT_FOR_BUFFER;
spin_unlock_irq(&dcmi->irqlock);
return 0;
}
@@ -548,9 +550,11 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)

spin_lock_irq(&dcmi->irqlock);

- if (dcmi->state == RUNNING && !dcmi->active) {
dcmi->active = buf;

+ if (dcmi->state == WAIT_FOR_BUFFER) {
+ dcmi->state = RUNNING;
+
dev_dbg(dcmi->dev, "Starting capture on buffer[%d] queued\n",
buf->vb.vb2_buf.index);

@@ -630,8 +634,6 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
/* Enable dcmi */
reg_set(dcmi->regs, DCMI_CR, CR_ENABLE);

- dcmi->state = RUNNING;
-
dcmi->sequence = 0;
dcmi->errors_count = 0;
dcmi->overrun_count = 0;
@@ -644,6 +646,7 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
*/
if (list_empty(&dcmi->buffers)) {
dev_dbg(dcmi->dev, "Start streaming is deferred to next buffer queueing\n");
+ dcmi->state = WAIT_FOR_BUFFER;
spin_unlock_irq(&dcmi->irqlock);
return 0;
}
@@ -653,6 +656,8 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)

dev_dbg(dcmi->dev, "Start streaming, starting capture\n");

+ dcmi->state = RUNNING;
+
spin_unlock_irq(&dcmi->irqlock);
ret = dcmi_start_capture(dcmi);
if (ret) {
--
1.9.1