Hi Laurent,
On Tue, Sep 19, 2023 at 04:32:48PM +0300, Laurent Pinchart wrote:
> Hi Sakari,
>
> Thank you for the patch.
>
> On Tue, Sep 19, 2023 at 03:17:27PM +0300, Sakari Ailus wrote:
> > Print debug level information on returned frame descriptors.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-subdev.c | 32 ++++++++++++++++++++++++++-
> > 1 file changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > index 7b087be3ff4f..504ca625b2bd 100644
> > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > @@ -15,6 +15,7 @@
> > #include <linux/module.h>
> > #include <linux/overflow.h>
> > #include <linux/slab.h>
> > +#include <linux/string.h>
> > #include <linux/types.h>
> > #include <linux/version.h>
> > #include <linux/videodev2.h>
> > @@ -309,9 +310,38 @@ static int call_set_selection(struct v4l2_subdev *sd,
> > static int call_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> > struct v4l2_mbus_frame_desc *fd)
> > {
> > + unsigned int i;
> > + int ret;
> > +
> > memset(fd, 0, sizeof(*fd));
> >
> > - return sd->ops->pad->get_frame_desc(sd, pad, fd);
> > + ret = sd->ops->pad->get_frame_desc(sd, pad, fd);
> > + if (ret)
> > + return ret;
> > +
> > + dev_dbg(sd->dev, "Frame descriptor on pad %u, type %s\n", pad,
> > + fd->type == V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL ? "parallel" :
> > + fd->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2 ? "CSI-2" :
> > + "unknown");
> > +
> > + for (i = 0; i < fd->num_entries; i++) {
> > + struct v4l2_mbus_frame_desc_entry *entry = &fd->entry[i];
> > + char buf[20] = "";
>
> Should this be sized for the worst case ? The vc and dt should not be
> large, but a buffer overflow on the stack in debug code if a subdev
> returns an incorrect value would be bad.
17 should be enough but it's not useful to use a size not divisible by 4 in
practice here.
>
> > +
> > + if (fd->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
> > + snprintf(buf, sizeof(buf), ", vc %u, dt 0x%2.2x",
>
> 0x%02x would be one character shorter ;-) Same below.
It would be, but I prefer the above notation as it's more generic.
>
> > + entry->bus.csi2.vc, entry->bus.csi2.dt);
> > +
> > + dev_dbg(sd->dev,
> > + "\tstream %u, code 0x%4.4x, lenght %u, flags%s%s%s\n",
>
> s/lenght/length/
Thanks, I'll fix this.
>
> > + entry->stream, entry->pixelcode, entry->length,
> > + entry->flags & V4L2_MBUS_FRAME_DESC_FL_LEN_MAX ?
> > + " LEN_MAX" : "",
> > + entry->flags & V4L2_MBUS_FRAME_DESC_FL_BLOB ?
> > + " BLOB" : "", buf);
>
> If no flags are set, you will get something like
>
> stream 0, code 0x1234, length ..., flags, vc 0, dt 0x2a
>
> Maybe printing the hex value for the flags would be simpler and clearer
> ?
How about adding the numerical value in addition to the strings?
The use of these flags is rare though. I could just remove the strings,
too.
--
Regards,
Sakari Ailus
