On Mon, Jul 17, 2017 at 3:45 PM, Hans Verkuil [off-list ref] wrote:

On 14/07/17 11:36, Arnd Bergmann wrote:

quoted

@@ -201,8 +202,9 @@ static int cx18_g_fmt_sliced_vbi_cap(struct file *file, void *fh,
       * digitizer/slicer.  Note, cx18_av_vbi() wipes the passed in
       * fmt->fmt.sliced under valid calling conditions
       */
-     if (v4l2_subdev_call(cx->sd_av, vbi, g_sliced_fmt, &fmt->fmt.sliced))
-             return -EINVAL;
+     ret = v4l2_subdev_call(cx->sd_av, vbi, g_sliced_fmt, &fmt->fmt.sliced);
+     if (ret)
+             return ret;

Please keep the -EINVAL here. I can't be 100% certain that returning 'ret' wouldn't
break something.

I think Dan was recommending the opposite here, if I understood you
both correctly:
he said we should propagate the error code unless we know it's wrong, while you
want to keep the current behavior to avoid introducing changes ;-)

I guess in either case, looking at the callers more carefully would be
a good idea.

quoted

-     return 0;
+     return ret;
 }

 int atomisp_flash_enable(struct atomisp_sub_device *asd, int num_frames)

This is all very hackish, though. I'm not terribly keen on this patch. It's not
clear to me *why* these warnings appear in your setup.

it's possible that this only happened with 'ccache', which first preprocesses
the source and the passes it with v4l2_subdev_call expanded into the
compiler. This means the line looks like

        if ((!(cx->sd_av) ? -ENODEV :
            (((cx->sd_av)->ops->vbi && (cx->sd_av)->ops->vbi->g_sliced_fmt) ?
               (cx->sd_av)->ops->vbi->g_sliced_fmt(cx->sd_av)),
&fmt->fmt.sliced) :
               -ENOIOCTLCMD))

The compiler now complains about the sub-expression that it sees for
cx->sd_av==NULL:

   if (-ENODEV)

which it considers nonsense because it is always true and the value gets
ignored.

Let me try again without ccache for now and see what warnings remain.
We can find a solution for those first, and then decide how to deal with
ccache.

        Arnd