Re: [PATCH v7 6/6] media: starfive: camss: Add VIN driver

Laurent Pinchart
2023-08-24T13:39:00Z

Hi Jack,

On Fri, Aug 04, 2023 at 07:14:22PM +0800, Jack Zhu wrote:
> On 2023/8/4 6:18, Laurent Pinchart wrote:
> > On Thu, Aug 03, 2023 at 10:44:50AM +0800, Jack Zhu wrote:
> >> On 2023/8/2 18:38, Laurent Pinchart wrote:
> >> > On Wed, Aug 02, 2023 at 05:58:26PM +0800, Jack Zhu wrote:
> >> >> On 2023/7/28 4:49, Laurent Pinchart wrote:
> >> >> > On Mon, Jun 19, 2023 at 07:28:38PM +0800, Jack Zhu wrote:
> >> >> >> Add Video In Controller driver for StarFive Camera Subsystem.
> >> >> >
> >> >> > I haven't reviewed this patch in details, as I have a high-level
> >> >> > question: why do you need VIN subdevs ? They don't seem to represent any
> >> >> > particular piece of hardware, their input and output formats are always
> >> >> > identical, and they're not used to configure registers. The contents of
> >> >> > this patch seems to belong to the video device, I think you can drop the
> >> >> > VIN subdevs.
> >> >>
> >> >> The VIN module corresponds to a hardware module, which is mainly responsible
> >> >> for data routing and partial interrupt management (when the image data does
> >> >> not pass through the isp but directly goes to the ddr), the relevant registers
> >> >> need to be configured.
> >> >
> >> > That's fine, but I don't think you need a subdev for it. As far as I
> >> > understand, the VIn modules are (more or less) DMA engines. You can just
> >> > model them as video devices, connected directly to the CSI-2 RX and ISP
> >> > source pads.
> >>
> >> The VIN hardware can also route input data, it can decide whether DVP sensor
> >> or MIPI sensor is used as input data.
> >>
> >> > Does the "vin0_wr" have the ability to capture raw data from the DVP
> >> > interface as well, or only from the CSI-2 RX ?
> >>
> >> Yes, the "vin0_wr" has the ability to capture raw data from the DVP
> >> interface.
> >
> > Then I would recommend something similar to the following media graph:
> >
> > digraph board {
> > rankdir=TB
> > imx219 [label="{{} | imx219 6-0010\n/dev/v4l-subdev0 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
> > imx219:port0 -> csi2rx:port0 [style=bold]
> > csi2rx [label="{{<port0> 0} | cdns_csi2rx.19800000.csi-bridge\n | {<port1> 1 | <port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
> > csi2rx:port1 -> vin:port0 [style=bold]
> > ov5640 [label="{{} | ov5640 6-0020\n/dev/v4l-subdev1 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
> > ov5640:port0 -> vin:port1 [style=bold]
> > vin [label="{{<port0> 0 | <port1> 1} | stf_vin0\n/dev/v4l-subdev2 | {<port2> 2}}", shape=Mrecord, style=filled, fillcolor=green]
> > vin:port2 -> raw_capture [style=dashed]
> > vin:port2 -> isp:port0 [style=dashed]
> > raw_capture [label="stf_vin0_wr_video0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
> > isp [label="{{<port0> 0} | stf_isp0\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
> > isp:port1 -> yuv_capture [style=bold]
> > yuv_capture [label="stf_vin0_isp0_video1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
> > }
> >
> > Here, the stf_vin0 subdev is used to route either the CSI-2 input or the
> > DVP input to the raw capture video device and the ISP.
> >
> > Does this match the hardware architecture ?
>
> Yes, but I have a question to ask, is there any way for stf_vin0 subdev
> to distinguish whether the current scene is 'raw_capture' or 'yuv_capture'?

Sorry about the late reply, I had missed your e-mail.

I'm not sure to follow you here. Do you mean differentiating between
capturing raw frames from stf_vin0_wr_video0 and YUV frames from
stf_vin0_isp0_video1 ? Are those mutually exclusive, or is it possible
to capture both raw frames and YUV frames at the same time ?

> > What are ports 2, 3 and 4 for in the CSI-2 RX ?
>
> port2-4 are useless, they should be created by 'cdns-csi2rx.c' by default.
>
> >> >> >> Signed-off-by: Jack Zhu <jack.zhu@starfivetech.com>
> >> >> >> ---
> >> >> >> .../media/platform/starfive/camss/Makefile | 4 +-
> >> >> >> .../media/platform/starfive/camss/stf_camss.c | 42 +-
> >> >> >> .../media/platform/starfive/camss/stf_camss.h | 2 +
> >> >> >> .../media/platform/starfive/camss/stf_vin.c | 1069 +++++++++++++++++
> >> >> >> .../media/platform/starfive/camss/stf_vin.h | 173 +++
> >> >> >> .../platform/starfive/camss/stf_vin_hw_ops.c | 192 +++
> >> >> >> 6 files changed, 1478 insertions(+), 4 deletions(-)
> >> >> >> create mode 100644 drivers/media/platform/starfive/camss/stf_vin.c
> >> >> >> create mode 100644 drivers/media/platform/starfive/camss/stf_vin.h
> >> >> >> create mode 100644 drivers/media/platform/starfive/camss/stf_vin_hw_ops.c
> >> >> >>
> >> >> >> diff --git a/drivers/media/platform/starfive/camss/Makefile b/drivers/media/platform/starfive/camss/Makefile
> >> >> >> index cdf57e8c9546..ef574e01ca47 100644
> >> >> >> --- a/drivers/media/platform/starfive/camss/Makefile
> >> >> >> +++ b/drivers/media/platform/starfive/camss/Makefile
> >> >> >> @@ -7,6 +7,8 @@ starfive-camss-objs += \
> >> >> >> stf_camss.o \
> >> >> >> stf_isp.o \
> >> >> >> stf_isp_hw_ops.o \
> >> >> >> - stf_video.o
> >> >> >> + stf_video.o \
> >> >> >> + stf_vin.o \
> >> >> >> + stf_vin_hw_ops.o
> >> >> >>
> >> >> >> obj-$(CONFIG_VIDEO_STARFIVE_CAMSS) += starfive-camss.o
> >> >> >> diff --git a/drivers/media/platform/starfive/camss/stf_camss.c b/drivers/media/platform/starfive/camss/stf_camss.c
> >> >> >> index 6f56b45f57db..834ea63eb833 100644
> >> >> >> --- a/drivers/media/platform/starfive/camss/stf_camss.c
> >> >> >> +++ b/drivers/media/platform/starfive/camss/stf_camss.c
> >> >> >> @@ -131,27 +131,61 @@ static int stfcamss_init_subdevices(struct stfcamss *stfcamss)
> >> >> >> return ret;
> >> >> >> }
> >> >> >>

--
Regards,

Laurent Pinchart