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media: staging: rkisp1: cap: don't set next buffer from rkisp1_vb2_buf_queue

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The function 'rkisp1_vb2_buf_queue' sets the next buffer directly
in case the capture is already streaming but no frame yet arrived
from the sensor. This is an optimization that tries to avoid
dropping a frame.
The call atomic_read(&cap->rkisp1->isp.frame_sequence) is used
to check if a frame arrived. Reading the 'frame_sequence' should
be avoided outside irq handlers to avoid race conditions.

This patch removes this optimization. Dropping of the first
frames can be avoided if userspace queues the buffers before
start streaming. If userspace starts queueing buffers
only after calling 'streamon' he risks frame drops anyway.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Acked-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Dafna Hirschfeld
2020-07-14 14:38:29 +02:00
committed by Mauro Carvalho Chehab
parent 2cc6a9fea0
commit aa86e0bbf2
1 changed files with 1 additions and 12 deletions
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13
drivers/staging/media/rkisp1/rkisp1-capture.c
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@@ -743,18 +743,7 @@ static void rkisp1_vb2_buf_queue(struct vb2_buffer *vb)
ispbuf->buff_addr[RKISP1_PLANE_CB]);
spin_lock_irqsave(&cap->buf.lock, flags);
/*
* If there's no next buffer assigned, queue this buffer directly
* as the next buffer, and update the memory interface.
*/
if (cap->is_streaming && !cap->buf.next &&
atomic_read(&cap->rkisp1->isp.frame_sequence) == -1) {
cap->buf.next = ispbuf;
rkisp1_set_next_buf(cap);
} else {
list_add_tail(&ispbuf->queue, &cap->buf.queue);
}
list_add_tail(&ispbuf->queue, &cap->buf.queue);
spin_unlock_irqrestore(&cap->buf.lock, flags);
}