linux-kernel - Re: [PATCH v6 3/9] v4l: platform: Add Renesas CEU driver

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Message-ID: <20180121172907.GO24926@w540>
Date:   Sun, 21 Jan 2018 18:29:07 +0100
From:   jacopo mondi <jacopo@...ndi.org>
To:     Hans Verkuil <hverkuil@...all.nl>
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        laurent.pinchart@...asonboard.com, magnus.damm@...il.com,
        geert@...der.be, mchehab@...nel.org, festevam@...il.com,
        sakari.ailus@....fi, robh+dt@...nel.org, mark.rutland@....com,
        pombredanne@...b.com, linux-renesas-soc@...r.kernel.org,
        linux-media@...r.kernel.org, linux-sh@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 3/9] v4l: platform: Add Renesas CEU driver

Hi Hans,

On Sun, Jan 21, 2018 at 11:23:12AM +0100, Hans Verkuil wrote:
> On 21/01/18 11:21, Hans Verkuil wrote:
> > On 21/01/18 10:53, jacopo mondi wrote:
> >> Hi Hans,
> >>
> >> On Fri, Jan 19, 2018 at 12:20:19PM +0100, Hans Verkuil wrote:
> >>> static int ov7670_g_parm(struct v4l2_subdev *sd, struct v4l2_streamparm *parms)
> >>> {
> >>>         struct v4l2_captureparm *cp = &parms->parm.capture;
> >>>         struct ov7670_info *info = to_state(sd);
> >>>
> >>>         if (parms->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
> >>>                 return -EINVAL;
> >>>
> >>> And parms->type is CAPTURE_MPLANE. Just drop this test from the ov7670 driver
> >>> in the g/s_parm functions. It shouldn't test for that since a subdev driver
> >>> knows nothing about buffer types.
> >>>
> >>
> >> I will drop that test in an additional patch part of next iteration of this series,
> >
> > Replace g/s_parm by g/s_frame_interval. Consider g/s_parm for subdev drivers as
> > deprecated (I'm working on a patch series to replace all g/s_parm uses by
> > g/s_frame_interval).
>
> Take a look here:
>
> https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=parm
>
> You probably want to use the patch 'v4l2-common: add g/s_parm helper functions'
> for the new ceu driver in your patch series. Feel free to add it.

Thanks, I have now re-based my series on top of your 'parm' branch,
and now I have silenced those errors on bad frame interval.

CEU g/s_parm now look like this:

static int ceu_g_parm(struct file *file, void *fh, struct v4l2_streamparm *a)
{
	struct ceu_device *ceudev = video_drvdata(file);
	int ret;

	ret = v4l2_g_parm(V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE,
			  ceudev->sd->v4l2_sd, a);
	if (ret)
		return ret;

	a->parm.capture.readbuffers = 0;

	return 0;
}

Very similar to what you've done on other platform drivers in this
commit:
https://git.linuxtv.org/hverkuil/media_tree.git/commit/?h=parm&id=a58956ef45cebaa5ce43a5f740fe04517b24a853

I have a question though (please bear with me a little more :)
I had to manually set a->parm.capture.readbuffers to 0 to silence the following
error in v4l2_compliance (which I have now updated to the most recent
remote HEAD):

 fail: v4l2-test-formats.cpp(1114): cap->readbuffers
                test VIDIOC_G/S_PARM: FAIL

		fail_on_test(cap->readbuffers > VIDEO_MAX_FRAME);
		if (!(node->g_caps() & V4L2_CAP_READWRITE))
			fail_on_test(cap->readbuffers);
		else if (node->g_caps() & V4L2_CAP_STREAMING)
			fail_on_test(!cap->readbuffers);

CEU does not support CAP_READWRITE, as it seems atmel-isc/isi do not, so
v4l2-compliance wants to have readbuffers set to 0. I wonder why in
the previously mentioned commit you didn't have to set readbuffers
explicitly to 0 for atmel-isc/isi as I had to for CEU. Will v4l2-compliance
fail if run on atmel-isc/isi with your commit, or am I missing something?

Thanks
   j