Dne petek, 26. avgust 2022 ob 20:32:15 CET je Paul Kocialkowski napisal(a): > The current implementation requires up to 3 buffers to properly > implement page flipping without losing frames: one is configured > before the video stream is started, one just after that and page > flipping is synchronized to the frame done interrupt. The comment in > the code mentions that "CSI will lookup the next dma buffer for next > frame before the current frame done IRQ triggered". > > Based on observations of the CSI unit behavior, it seems that the > buffer DMA address is sampled when the frame scan begins (in addition > to starting the stream), which corresponds to the vblank interrupt > that hits just before the frame-done interrupt of the previous frame. > > As a result, the address configured at the frame done interrupt is not > actually used for the next frame but for the one after that. > > This proposal changes the page flipping sync point to the vsync > interrupt, which allows the DMA address to be sampled for the next > frame instead and allows operating with only two buffers. > > In addition to the change in the sync point, the code is refactored > to introduce a notion of state that clarifies tracking of the buffers > with tidy functions. > > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> Acked-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx> Best regards, Jernej
