[PATCH] media: rkisp1: Reduce min_queued_buffers to 1

[Jacopo Mondi]

There apparently is no reason to require 3 queued buffers to call
streamon() for the RkISP1 as the driver operates with a scratch buffer
where frames can be directed to if there's no available buffer provided
by userspace.

Reduce the number of required buffers to 1 to allow applications to
operate with a single queued buffer.

Tested with libcamera, by operating with a single capture a request. The
same request (and associated capture buffer) gets recycled once
completed. This of course causes a frame rate drop but doesn't hinder
operations.

Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
---

Adam,
   a few months ago you were exercizing your pinhole app with a single capture
request for StillCapture operations and you got the video device to hang because
no enough buffers where provided.

This small change should be enough to unblock you. Could you maybe give it a
spin if you're still working on this ?

Thanks
   j
---

 drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
index 2bddb4fa8a5c..34adaecdee54 100644
--- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
+++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
@@ -35,8 +35,6 @@
 #define RKISP1_SP_DEV_NAME	RKISP1_DRIVER_NAME "_selfpath"
 #define RKISP1_MP_DEV_NAME	RKISP1_DRIVER_NAME "_mainpath"

-#define RKISP1_MIN_BUFFERS_NEEDED 3
-
 enum rkisp1_plane {
 	RKISP1_PLANE_Y	= 0,
 	RKISP1_PLANE_CB	= 1,
@@ -1563,7 +1561,7 @@ static int rkisp1_register_capture(struct rkisp1_capture *cap)
 	q->ops = &rkisp1_vb2_ops;
 	q->mem_ops = &vb2_dma_contig_memops;
 	q->buf_struct_size = sizeof(struct rkisp1_buffer);
-	q->min_queued_buffers = RKISP1_MIN_BUFFERS_NEEDED;
+	q->min_queued_buffers = 1;
 	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
 	q->lock = &node->vlock;
 	q->dev = cap->rkisp1->dev;
--
2.46.1