diff options
| author | Robert Jarzmik <robert.jarzmik@free.fr> | 2009-04-24 11:58:35 -0400 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2009-06-16 17:20:44 -0400 |
| commit | 56600093644c6929a7d1809dab5b8265532df045 (patch) | |
| tree | 12d9986af549cc57642720889d646af3bc64bfc9 /Documentation/video4linux | |
| parent | c09b77806e692d8e58c55b4f4592a855b95f13cd (diff) | |
V4L/DVB (11613): pxa_camera: Documentation of the FSM
After DMA redesign, the pxa_camera dynamic behaviour should
be documented so that future contributors understand how it
works, and improve it.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/video4linux')
| -rw-r--r-- | Documentation/video4linux/pxa_camera.txt | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/Documentation/video4linux/pxa_camera.txt b/Documentation/video4linux/pxa_camera.txt index b1137f9a53eb..4f6d0ca01956 100644 --- a/Documentation/video4linux/pxa_camera.txt +++ b/Documentation/video4linux/pxa_camera.txt | |||
| @@ -26,6 +26,55 @@ Global video workflow | |||
| 26 | 26 | ||
| 27 | Once the last buffer is filled in, the QCI interface stops. | 27 | Once the last buffer is filled in, the QCI interface stops. |
| 28 | 28 | ||
| 29 | c) Capture global finite state machine schema | ||
| 30 | |||
| 31 | +----+ +---+ +----+ | ||
| 32 | | DQ | | Q | | DQ | | ||
| 33 | | v | v | v | ||
| 34 | +-----------+ +------------------------+ | ||
| 35 | | STOP | | Wait for capture start | | ||
| 36 | +-----------+ Q +------------------------+ | ||
| 37 | +-> | QCI: stop | ------------------> | QCI: run | <------------+ | ||
| 38 | | | DMA: stop | | DMA: stop | | | ||
| 39 | | +-----------+ +-----> +------------------------+ | | ||
| 40 | | / | | | ||
| 41 | | / +---+ +----+ | | | ||
| 42 | |capture list empty / | Q | | DQ | | QCI Irq EOF | | ||
| 43 | | / | v | v v | | ||
| 44 | | +--------------------+ +----------------------+ | | ||
| 45 | | | DMA hotlink missed | | Capture running | | | ||
| 46 | | +--------------------+ +----------------------+ | | ||
| 47 | | | QCI: run | +-----> | QCI: run | <-+ | | ||
| 48 | | | DMA: stop | / | DMA: run | | | | ||
| 49 | | +--------------------+ / +----------------------+ | Other | | ||
| 50 | | ^ /DMA still | | channels | | ||
| 51 | | | capture list / running | DMA Irq End | not | | ||
| 52 | | | not empty / | | finished | | ||
| 53 | | | / v | yet | | ||
| 54 | | +----------------------+ +----------------------+ | | | ||
| 55 | | | Videobuf released | | Channel completed | | | | ||
| 56 | | +----------------------+ +----------------------+ | | | ||
| 57 | +-- | QCI: run | | QCI: run | --+ | | ||
| 58 | | DMA: run | | DMA: run | | | ||
| 59 | +----------------------+ +----------------------+ | | ||
| 60 | ^ / | | | ||
| 61 | | no overrun / | overrun | | ||
| 62 | | / v | | ||
| 63 | +--------------------+ / +----------------------+ | | ||
| 64 | | Frame completed | / | Frame overran | | | ||
| 65 | +--------------------+ <-----+ +----------------------+ restart frame | | ||
| 66 | | QCI: run | | QCI: stop | --------------+ | ||
| 67 | | DMA: run | | DMA: stop | | ||
| 68 | +--------------------+ +----------------------+ | ||
| 69 | |||
| 70 | Legend: - each box is a FSM state | ||
| 71 | - each arrow is the condition to transition to another state | ||
| 72 | - an arrow with a comment is a mandatory transition (no condition) | ||
| 73 | - arrow "Q" means : a buffer was enqueued | ||
| 74 | - arrow "DQ" means : a buffer was dequeued | ||
| 75 | - "QCI: stop" means the QCI interface is not enabled | ||
| 76 | - "DMA: stop" means all 3 DMA channels are stopped | ||
| 77 | - "DMA: run" means at least 1 DMA channel is still running | ||
| 29 | 78 | ||
| 30 | DMA usage | 79 | DMA usage |
| 31 | --------- | 80 | --------- |