Messages in this thread | | | Date | Tue, 28 Nov 2023 10:27:52 +0100 | Subject | Re: [PATCH 02/55] media: test-drivers: Stop abusing of min_buffers_needed field | From | Benjamin Gaignard <> |
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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
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