On Tue, Nov 28, 2023 at 6:31 PM Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx> wrote: > > > Le 27/11/2023 à 18:07, Laurent Pinchart a écrit : > > Hi Benjamin, > > > > Thank you for the patch. > > > > On Mon, Nov 27, 2023 at 05:54:06PM +0100, Benjamin Gaignard wrote: > >> 'min_buffers_needed' is suppose to be used to indicate the number > >> of buffers needed by DMA engine to start streaming. > >> imx8-isi driver doesn't use DMA engine and just want to specify > > What do you mean, "doesn't use DMA engine" ? The ISI surely has DMA > > engines :-) > > I have done assumption on drivers given if they use or dma_* functions. I suspect the use of vb2_dma_sg_plane_desc() and vb2_dma_contig_plane_dma_addr() may be more correlated to whether there is a DMA involved or not. Usually V4L2 drivers don't really have to deal with the DMA API explicitly, because the vb2 framework handles most of the work. Best regards, Tomasz > I have considers that all PCI drivers are using DMA engine and > I don't know the design for each drivers so I hope to get this information > from maintainers and fix that in v2. > If imx8-isi driver needs a minimum number of buffers before start streaming > I will do a v2 and use min_dma_buffers_needed instead. > > Regards, > Benjamin > > > > >> the minimum number of buffers to allocate when calling VIDIOC_REQBUFS. > >> That 'min_reqbufs_allocation' field purpose so use it. > >> > >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx> > >> CC: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > >> CC: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> > >> CC: Shawn Guo <shawnguo@xxxxxxxxxx> > >> CC: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> > >> CC: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx> > >> CC: Fabio Estevam <festevam@xxxxxxxxx> > >> CC: NXP Linux Team <linux-imx@xxxxxxx> > >> --- > >> drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c > >> index 49bca2b01cc6..81673ff9084b 100644 > >> --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c > >> +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c > >> @@ -1453,7 +1453,7 @@ int mxc_isi_video_register(struct mxc_isi_pipe *pipe, > >> q->mem_ops = &vb2_dma_contig_memops; > >> q->buf_struct_size = sizeof(struct mxc_isi_buffer); > >> q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC; > >> - q->min_buffers_needed = 2; > >> + q->min_reqbufs_allocation = 2; > >> q->lock = &video->lock; > >> q->dev = pipe->isi->dev; > >>
