Hi, Laurent
>
> On Mon, Aug 19, 2024 at 01:37:30AM +0000, Changhuang Liang wrote:
> > > On Mon, Aug 12, 2024 at 12:13:03PM +0000, Changhuang Liang wrote:
> > > > > On Mon, Aug 12, 2024 at 09:43:47AM +0000, Changhuang Liang
> wrote:
> > > > > > > On Fri, Aug 09, 2024 at 12:12:01PM +0000, Changhuang Liang
> wrote:
> > > > > > > > > On Fri, Apr 19, 2024 at 01:19:55AM -0700, Changhuang Liang
> wrote:
> > > > > > > > > > Add multiple resolution support for video "capture_raw"
> device.
> > > > > > > > > > Otherwise it will capture the wrong image data if the width is
> not 1920.
> > > > > > > > > >
> > > > > > > > > > Fixes: e080f339c80a ("media: staging: media: starfive:
> > > > > > > > > > camss: Add capture driver")
> > > > > > > > > >
> > > > > > > > > > Signed-off-by: Changhuang Liang
> > > > > > > > > > <changhuang.liang@xxxxxxxxxxxxxxxx>
> > > > > > > > > > ---
> > > > > > > > > > drivers/staging/media/starfive/camss/stf-capture.c |
> > > > > > > > > > 5 ++++-
> > > > > > > > > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > > > > > > > > >
> > > > > > > > > > diff --git
> > > > > > > > > > a/drivers/staging/media/starfive/camss/stf-capture.c
> > > > > > > > > > b/drivers/staging/media/starfive/camss/stf-capture.c
> > > > > > > > > > index ec5169e7b391..9e853ff2596a 100644
> > > > > > > > > > ---
> > > > > > > > > > a/drivers/staging/media/starfive/camss/stf-capture.c
> > > > > > > > > > +++ b/drivers/staging/media/starfive/camss/stf-capture
> > > > > > > > > > +++ .c
> > > > > > > > > > @@ -177,9 +177,12 @@ static void stf_channel_set(struct
> stfcamss_video *video) {
> > > > > > > > > > struct stf_capture *cap = to_stf_capture(video);
> > > > > > > > > > struct stfcamss *stfcamss = cap->video.stfcamss;
> > > > > > > > > > + struct v4l2_pix_format *pix;
> > > > > > > > >
> > > > > > > > > This variable can be const as you don't modify the format.
> > > > > > > > >
> > > > > > > > > > u32 val;
> > > > > > > > > >
> > > > > > > > > > if (cap->type == STF_CAPTURE_RAW) {
> > > > > > > > > > + pix = &video->active_fmt.fmt.pix;
> > > > > > > > >
> > > > > > > > > And it can be declared and initialized here:
> > > > > > > > >
> > > > > > > > > const struct v4l2_pix_format *pix =
> > > > > > > > > &video->active_fmt.fmt.pix;
> > > > > > > > >
> > > > > > > > > > +
> > > > > > > > > > val = stf_syscon_reg_read(stfcamss,
> VIN_CHANNEL_SEL_EN);
> > > > > > > > > > val &= ~U0_VIN_CHANNEL_SEL_MASK;
> > > > > > > > > > val |= CHANNEL(0);
> > > > > > > > > > @@ -193,7 +196,7 @@ static void stf_channel_set(struct
> stfcamss_video *video)
> > > > > > > > > > val |= PIXEL_HEIGH_BIT_SEL(0);
> > > > > > > > > >
> > > > > > > > > > val &= ~U0_VIN_PIX_CNT_END_MASK;
> > > > > > > > > > - val |= PIX_CNT_END(IMAGE_MAX_WIDTH / 4 - 1);
> > > > > > > > > > + val |= PIX_CNT_END(pix->width / 4 - 1);
> > > > > > > > >
> > > > > > > > > Is there no need to consider the image height as well ?
> > > > > > > > > How does the driver prevent buffer overflows if the
> > > > > > > > > sensor sends more data than expected ?
> > > > > > > >
> > > > > > > > Our hardware will confirm a frame of data through vblank
> > > > > > > > signal, so there is no image height configuration.
> > > > > > >
> > > > > > > What happens if the system expects, for instance, a
> > > > > > > 1920x1080
> > > > > > > RAW8 image, and allocates a buffer of of 1920x1080 bytes,
> > > > > > > but the sensor outputs more lines ? Does the camera hardware
> > > > > > > in the SoC offer an option to prevent buffer overruns ?
> > > > > >
> > > > > > The hardware can confirm the image height by using the VSYNC
> signal.
> > > > > >
> > > > > > Image will transfer when VSYNC is high.
> > > > > >
> > > > > > VSYNC time = (width + h_blank) * height;
> > > > >
> > > > > What I'm trying to understand is what happens if the ISP is
> > > > > configured for
> > > > > 1080 lines, but the camera sensor sends more than 1080 lines
> > > > > (the VSYNC signal is active for more than 1080 lines). Where in
> > > > > the driver is the hardware configure with the 1080 lines limit to avoid
> buffer overflows ?
> > > >
> > > > If is "capture_raw" video device, no image height can be configured.
> > >
> > > In that case what happens if the camera sensor sends more lines than
> > > expected ? Will the raw video device write past the end of the buffer ?
> >
> > Yes, the buffer will overflows, so we will use the software restrictions.
> > Implement .link_validate hooks for the CSI2RX subdev and "capture_raw"
> video device.
>
> Is there an IOMMU in the system that could help preventing buffer overflows
> to reach system memory ?
>
JH7110 SoC has no IOMMU.
> > > If so, is there a way to guard against that ?
> > >
> > > > If is "capture_yuv" video device, it will be set by stf_isp_config_crop.
> > >
> > > Thank you, that's the information I was looking for.
>
> --
Regards,
Changhuang
