[PATCH 05/12] media: stm32: dcmi: rework spin_lock calls

Alain Volmat
2025-12-18T18:45:20Z

Rework of the spin_lock calls in preparation of the rework
of the data handling of the driver. Keep it straight forward
with basically spin_lock protection around everything except
dmaengine calls that might sleep (ex: synchronize / terminate)

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
---
drivers/media/platform/st/stm32/stm32-dcmi.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/media/platform/st/stm32/stm32-dcmi.c b/drivers/media/platform/st/stm32/stm32-dcmi.c
index fa33acc34eab..1015f2d88f54 100644
--- a/drivers/media/platform/st/stm32/stm32-dcmi.c
+++ b/drivers/media/platform/st/stm32/stm32-dcmi.c
@@ -227,25 +227,18 @@ static int dcmi_restart_capture(struct stm32_dcmi *dcmi)
{
struct dcmi_buf *buf;

- spin_lock_irq(&dcmi->irqlock);
-
- if (dcmi->state != RUNNING) {
- spin_unlock_irq(&dcmi->irqlock);
+ if (dcmi->state != RUNNING)
return -EINVAL;
- }

/* Restart a new DMA transfer with next buffer */
if (list_empty(&dcmi->buffers)) {
dev_dbg(dcmi->dev, "Capture restart is deferred to next buffer queueing\n");
dcmi->state = WAIT_FOR_BUFFER;
- spin_unlock_irq(&dcmi->irqlock);
return 0;
}
buf = list_entry(dcmi->buffers.next, struct dcmi_buf, list);
dcmi->active = buf;

- spin_unlock_irq(&dcmi->irqlock);
-
return dcmi_start_capture(dcmi, buf);
}

@@ -370,8 +363,10 @@ static void dcmi_process_jpeg(struct stm32_dcmi *dcmi)
* buffer payload.
*/

+ spin_unlock_irq(&dcmi->irqlock);
/* Drain DMA */
dmaengine_synchronize(dcmi->dma_chan);
+ spin_lock_irq(&dcmi->irqlock);

/* Get DMA residue to get JPEG size */
status = dmaengine_tx_status(dcmi->dma_chan, dcmi->dma_cookie, &state);
@@ -386,8 +381,10 @@ static void dcmi_process_jpeg(struct stm32_dcmi *dcmi)
dcmi_buffer_done(dcmi, buf, 0, -EIO);
}

+ spin_unlock_irq(&dcmi->irqlock);
/* Abort DMA operation */
dmaengine_terminate_sync(dcmi->dma_chan);
+ spin_lock_irq(&dcmi->irqlock);

/* Restart capture */
if (dcmi_restart_capture(dcmi))
@@ -413,8 +410,10 @@ static irqreturn_t dcmi_irq_thread(int irq, void *arg)
spin_unlock_irq(&dcmi->irqlock);
dmaengine_terminate_sync(dcmi->dma_chan);

+ spin_lock_irq(&dcmi->irqlock);
if (dcmi_restart_capture(dcmi))
dev_err(dcmi->dev, "%s: Cannot restart capture\n", __func__);
+ spin_unlock_irq(&dcmi->irqlock);

return IRQ_HANDLED;
}
@@ -424,8 +423,8 @@ static irqreturn_t dcmi_irq_thread(int irq, void *arg)
if (dcmi->sd_format->fourcc == V4L2_PIX_FMT_JPEG &&
dcmi->misr & IT_FRAME) {
/* JPEG received */
- spin_unlock_irq(&dcmi->irqlock);
dcmi_process_jpeg(dcmi);
+ spin_unlock_irq(&dcmi->irqlock);
return IRQ_HANDLED;
}

@@ -599,11 +598,9 @@ static void dcmi_buf_queue(struct vb2_buffer *vb)
dev_dbg(dcmi->dev, "Starting capture on buffer[%d] queued\n",
buf->vb.vb2_buf.index);

- spin_unlock_irq(&dcmi->irqlock);
if (dcmi_start_capture(dcmi, buf))
dev_err(dcmi->dev, "%s: Cannot restart capture on overflow or error\n",
__func__);
- return;
}

spin_unlock_irq(&dcmi->irqlock);
@@ -812,11 +809,11 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)

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

- spin_unlock_irq(&dcmi->irqlock);
ret = dcmi_start_capture(dcmi, buf);
if (ret) {
dev_err(dcmi->dev, "%s: Start streaming failed, cannot start capture\n",
__func__);
+ spin_unlock_irq(&dcmi->irqlock);
goto err_pipeline_stop;
}

@@ -826,6 +823,8 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
else
reg_set(dcmi->regs, DCMI_IER, IT_OVR | IT_ERR);

+ spin_unlock_irq(&dcmi->irqlock);
+
return 0;

err_pipeline_stop:

--
2.34.1