'min_buffers_needed' is suppose to be used to indicate the number
of buffers needed by DMA engine to start streaming.
Obvious test-drivers don't use DMA engine and just want to specify
the minimum number of buffers to allocate when calling VIDIOC_REQBUFS.
That 'min_reqbufs_allocation' field purpose so use it.
While at it rename function parameter.
Signed-off-by: Benjamin Gaignard <[email protected]>
CC: Shuah Khan <[email protected]>
CC: Kieran Bingham <[email protected]>
---
drivers/media/test-drivers/vimc/vimc-capture.c | 2 +-
drivers/media/test-drivers/vivid/vivid-core.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/media/test-drivers/vimc/vimc-capture.c b/drivers/media/test-drivers/vimc/vimc-capture.c
index aa944270e716..97693561f1e4 100644
--- a/drivers/media/test-drivers/vimc/vimc-capture.c
+++ b/drivers/media/test-drivers/vimc/vimc-capture.c
@@ -432,7 +432,7 @@ static struct vimc_ent_device *vimc_capture_add(struct vimc_device *vimc,
q->mem_ops = vimc_allocator == VIMC_ALLOCATOR_DMA_CONTIG
? &vb2_dma_contig_memops : &vb2_vmalloc_memops;
q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
- q->min_buffers_needed = 2;
+ q->min_reqbufs_allocation = 2;
q->lock = &vcapture->lock;
q->dev = v4l2_dev->dev;
diff --git a/drivers/media/test-drivers/vivid/vivid-core.c b/drivers/media/test-drivers/vivid/vivid-core.c
index 353f035fcd19..b4e888ac6016 100644
--- a/drivers/media/test-drivers/vivid/vivid-core.c
+++ b/drivers/media/test-drivers/vivid/vivid-core.c
@@ -861,7 +861,7 @@ static const struct media_device_ops vivid_media_ops = {
static int vivid_create_queue(struct vivid_dev *dev,
struct vb2_queue *q,
u32 buf_type,
- unsigned int min_buffers_needed,
+ unsigned int min_reqbufs_allocation,
const struct vb2_ops *ops)
{
if (buf_type == V4L2_BUF_TYPE_VIDEO_CAPTURE && dev->multiplanar)
@@ -898,7 +898,7 @@ static int vivid_create_queue(struct vivid_dev *dev,
q->mem_ops = allocators[dev->inst] == 1 ? &vb2_dma_contig_memops :
&vb2_vmalloc_memops;
q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
- q->min_buffers_needed = supports_requests[dev->inst] ? 0 : min_buffers_needed;
+ q->min_reqbufs_allocation = supports_requests[dev->inst] ? 0 : min_reqbufs_allocation;
q->lock = &dev->mutex;
q->dev = dev->v4l2_dev.dev;
q->supports_requests = supports_requests[dev->inst];
--
2.39.2
On 11/27/23 09:54, Benjamin Gaignard wrote:
> 'min_buffers_needed' is suppose to be used to indicate the number
> of buffers needed by DMA engine to start streaming.
> Obvious test-drivers don't use DMA engine and just want to specify
> the minimum number of buffers to allocate when calling VIDIOC_REQBUFS.
> That 'min_reqbufs_allocation' field purpose so use it.
> While at it rename function parameter.
>
So how ate the test-drivers currently abusing this field
and how does this change benefit?
I don't have objections to this change, I want to understand
it a bit more. I would like to see more details on why this
change is needed.
thanks,
-- Shuah
Le 27/11/2023 à 18:00, Shuah Khan a écrit :
> On 11/27/23 09:54, Benjamin Gaignard wrote:
>> 'min_buffers_needed' is suppose to be used to indicate the number
>> of buffers needed by DMA engine to start streaming.
>> Obvious test-drivers don't use DMA engine and just want to specify
>> the minimum number of buffers to allocate when calling VIDIOC_REQBUFS.
>> That 'min_reqbufs_allocation' field purpose so use it.
>> While at it rename function parameter.
>>
>
> So how ate the test-drivers currently abusing this field
> and how does this change benefit?
In videobuf2-core.h min_buffers_needed is documemented as:
"the minimum number of buffers needed before @start_streaming can be called.
Used when a DMA engine cannot be started unless at least this number of buffers have been queued into the driver."
Test-drivers don't use DMA engine so they (ab)use of this variable, like Hans said in this RFC:
https://www.spinics.net/lists/linux-media/msg244455.html
The goal of this series is to distinguish the minimum number of buffers to be allocated in VIDIOC_REQBUF
versus the minimum numbers of buffers needed before start streaming.
Regards,
Benjamin
>
> I don't have objections to this change, I want to understand
> it a bit more. I would like to see more details on why this
> change is needed.
>
> thanks,
> -- Shuah