linux-kernel - [PATCH v2 08/25] media: atmel: atmel-isc-base: use streaming status when queueing buffers

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Date:   Fri, 12 Nov 2021 16:24:52 +0200
From:   Eugen Hristev <eugen.hristev@...rochip.com>
To:     <linux-media@...r.kernel.org>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <jacopo@...ndi.org>,
        <laurent.pinchart@...asonboard.com>, <sakari.ailus@....fi>,
        <nicolas.ferre@...rochip.com>,
        Eugen Hristev <eugen.hristev@...rochip.com>
Subject: [PATCH v2 08/25] media: atmel: atmel-isc-base: use streaming status when queueing buffers

During experiments with libcamera, it looks like vb2_is_streaming returns
true before our start streaming is called.
Order of operations is streamon -> queue -> start_streaming
ISC would have started the DMA immediately when a buffer is being added
to the vbqueue if the queue is streaming.
It is more safe to start the DMA after the start streaming of the driver is
called.
Thus, even if vb2queue is streaming, add the buffer to the dma queue of the
driver instead of actually starting the DMA process, if the start streaming
has not been called yet.

Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
---
 drivers/media/platform/atmel/atmel-isc-base.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
index 26a6090f056c..e6c9071c04f0 100644
--- a/drivers/media/platform/atmel/atmel-isc-base.c
+++ b/drivers/media/platform/atmel/atmel-isc-base.c
@@ -441,12 +441,14 @@ static void isc_buffer_queue(struct vb2_buffer *vb)
 	unsigned long flags;
 
 	spin_lock_irqsave(&isc->dma_queue_lock, flags);
-	if (!isc->cur_frm && list_empty(&isc->dma_queue) &&
-		vb2_is_streaming(vb->vb2_queue)) {
+
+	if (!isc->cur_frm && list_empty(&isc->dma_queue) && !isc->stop) {
 		isc->cur_frm = buf;
 		isc_start_dma(isc);
-	} else
+	} else {
 		list_add_tail(&buf->list, &isc->dma_queue);
+	}
+
 	spin_unlock_irqrestore(&isc->dma_queue_lock, flags);
 }
 
@@ -1014,7 +1016,7 @@ static int isc_s_fmt_vid_cap(struct file *file, void *priv,
 {
 	struct isc_device *isc = video_drvdata(file);
 
-	if (vb2_is_streaming(&isc->vb2_vidq))
+	if (!isc->stop)
 		return -EBUSY;
 
 	return isc_set_fmt(isc, f);
@@ -1536,7 +1538,7 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl)
 
 		isc_update_awb_ctrls(isc);
 
-		if (vb2_is_streaming(&isc->vb2_vidq)) {
+		if (!isc->stop) {
 			/*
 			 * If we are streaming, we can update profile to
 			 * have the new settings in place.
@@ -1552,8 +1554,7 @@ static int isc_s_awb_ctrl(struct v4l2_ctrl *ctrl)
 		}
 
 		/* if we have autowhitebalance on, start histogram procedure */
-		if (ctrls->awb == ISC_WB_AUTO &&
-		    vb2_is_streaming(&isc->vb2_vidq) &&
+		if (ctrls->awb == ISC_WB_AUTO && !isc->stop &&
 		    ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code))
 			isc_set_histogram(isc, true);
 
@@ -1829,6 +1830,8 @@ static int isc_async_complete(struct v4l2_async_notifier *notifier)
 	struct vb2_queue *q = &isc->vb2_vidq;
 	int ret = 0;
 
+	isc->stop = true;
+
 	INIT_WORK(&isc->awb_work, isc_awb_work);
 
 	ret = v4l2_device_register_subdev_nodes(&isc->v4l2_dev);
-- 
2.25.1