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pipeline: rpi: Increase buffer import count to 32

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Hardcode the maximum number of buffers imported to the V4L2 video device
to 32. This only has a minor disadvantage of over-allocating cache slots
and V4L2 buffer indexes, but does allow more headroom for using dma
buffers allocated from outside of libcamera.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Naushir Patuck 2023-07-25 09:55:37 +01:00
parent ae9bcb2155
commit 1107999f71
1 changed files with 11 additions and 25 deletions
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36
src/libcamera/pipeline/rpi/common/rpi_stream.cpp
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@ -8,6 +8,9 @@
#include <libcamera/base/log.h>
/* Maximum number of buffer slots to allocate in the V4L2 device driver. */
static constexpr unsigned int maxV4L2BufferCount = 32;
namespace libcamera {
LOG_DEFINE_CATEGORY(RPISTREAM)
@ -95,34 +98,17 @@ int Stream::prepareBuffers(unsigned int count)
int ret;
if (!(flags_ & StreamFlag::ImportOnly)) {
if (count) {
/* Export some frame buffers for internal use. */
ret = dev_->exportBuffers(count, &internalBuffers_);
if (ret < 0)
return ret;
/* Export some frame buffers for internal use. */
ret = dev_->exportBuffers(count, &internalBuffers_);
if (ret < 0)
return ret;
/* Add these exported buffers to the internal/external buffer list. */
setExportedBuffers(&internalBuffers_);
resetBuffers();
}
/* We must import all internal/external exported buffers. */
count = bufferMap_.size();
/* Add these exported buffers to the internal/external buffer list. */
setExportedBuffers(&internalBuffers_);
resetBuffers();
}
/*
* If this is an external stream, we must allocate slots for buffers that
* might be externally allocated. We have no indication of how many buffers
* may be used, so this might overallocate slots in the buffer cache.
* Similarly, if this stream is only importing buffers, we do the same.
*
* \todo Find a better heuristic, or, even better, an exact solution to
* this issue.
*/
if ((flags_ & StreamFlag::External) || (flags_ & StreamFlag::ImportOnly))
count = count * 2;
return dev_->importBuffers(count);
return dev_->importBuffers(maxV4L2BufferCount);
}
int Stream::queueBuffer(FrameBuffer *buffer)