Hi Luca, Apologies for the delayed response. > -----Original Message----- > From: Luca Ceresoli [mailto:luca@xxxxxxxxxxxxxxxx] > Sent: Monday, February 11, 2019 8:01 PM > To: Vishal Sagar <vsagar@xxxxxxxxxx>; Vishal Sagar <vishal.sagar@xxxxxxxxxx>; > Hyun Kwon <hyunk@xxxxxxxxxx>; laurent.pinchart@xxxxxxxxxxxxxxxx; > mchehab@xxxxxxxxxx; robh+dt@xxxxxxxxxx; mark.rutland@xxxxxxx; Michal > Simek <michals@xxxxxxxxxx>; linux-media@xxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; sakari.ailus@xxxxxxxxxxxxxxx; > hans.verkuil@xxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; Dinesh Kumar <dineshk@xxxxxxxxxx>; Sandip Kothari > <sandipk@xxxxxxxxxx> > Subject: Re: [PATCH v3 2/2] media: v4l: xilinx: Add Xilinx MIPI CSI-2 Rx > Subsystem > > Hi, > > thanks for the quick reply. > > On 11/02/19 13:43, Vishal Sagar wrote: > >>> +static int xcsi2rxss_start_stream(struct xcsi2rxss_state *state) > >>> +{ > >>> + struct xcsi2rxss_core *core = &state->core; > >>> + int ret = 0; > >>> + > >>> + xcsi2rxss_enable(core); > >>> + > >>> + ret = xcsi2rxss_reset(core); > >>> + if (ret < 0) { > >>> + state->streaming = false; > >>> + return ret; > >>> + } > >>> + > >>> + xcsi2rxss_intr_enable(core); > >>> + state->streaming = true; > >> > >> Shouldn't you propagate s_stream to the upstream subdev here calling > >> v4l2_subdev_call(..., ..., s_stream, 1)? > >> > > > > This is done by the xvip_pipeline_start_stop() in xilinx-dma.c for Xilinx Video > pipeline. > > Indeed it does, however other CSI2 RX drivers do propagate s_stream in > their own s_stream. Not strictly related to this driver, but what's the > logic for having these two different behaviors? > I am not really sure about this. I agree with what you say but in case the s_stream() is implemented here, then the sensor's s_stream() will be called twice. I don't think this would be the correct behavior. > Also xvip_pipeline_start_stop() only follows the graph through > entity->pads[0], so it looks like it cannot handle entities with > multiple sink pads. How would it be able to handle e.g. the AXI4-Stream > Switch [0], which has 2+ sink pads? > I agree with you about this. There should be a different mechanism for this. Regards Vishal Sagar > [0] > https://www.xilinx.com/support/documentation/ip_documentation/axis_infra > structure_ip_suite/v1_1/pg085-axi4stream-infrastructure.pdf > (page 16). > > -- > Luca
