Re: [RFC PATCH V1 6/6] platform: mtk-isp: Add Mediatek DIP driver

[Frederic Chen <frederic.chen@mediatek.com>]

Dear Tomasz,

Would you comment on the following points in further? Thank you for the
review.

On Thu, 2019-05-09 at 18:48 +0900, Tomasz Figa wrote:
> Hi Frederic,
> 

[snip]

> > +int mtk_dip_pipe_job_start(struct mtk_dip_pipe *dip_pipe,
> > +                          struct mtk_dip_pipe_job_info *pipe_job_info)
> > +{
> > +       struct platform_device *pdev = dip_pipe->dip_dev->pdev;
> > +       int ret;
> > +       int out_img_buf_idx;
> > +       struct img_ipi_frameparam dip_param;
> > +       struct mtk_dip_dev_buffer *dev_buf_in;
> > +       struct mtk_dip_dev_buffer *dev_buf_out;
> > +       struct mtk_dip_dev_buffer *dev_buf_tuning;
> > +
> > +       if (!pipe_job_info) {
> > +               dev_err(&pdev->dev,
> > +                       "pipe_job_info(%p) in start can't be NULL\n",
> > +                       pipe_job_info);
> > +               return -EINVAL;
> > +       }
> 
> This should be impossible to happen.
> 
> > +
> > +       /* We need RAW and at least MDP0 or MDP 1 buffer */
> > +       if (!pipe_job_info->buf_map[MTK_DIP_VIDEO_NODE_ID_RAW_OUT] ||
> > +           (!pipe_job_info->buf_map[MTK_DIP_VIDEO_NODE_ID_MDP0_CAPTURE] &&
> > +                !pipe_job_info->buf_map[MTK_DIP_VIDEO_NODE_ID_MDP1_CAPTURE])){
> > +               struct mtk_dip_dev_buffer **map = pipe_job_info->buf_map;
> > +
> > +               dev_dbg(&pdev->dev,
> > +                       "can't trigger job: raw(%p), mdp0(%p), mdp1(%p)\n",
> > +                       map[MTK_DIP_VIDEO_NODE_ID_RAW_OUT],
> > +                       map[MTK_DIP_VIDEO_NODE_ID_MDP0_CAPTURE],
> > +                       map[MTK_DIP_VIDEO_NODE_ID_MDP1_CAPTURE]);
> > +               return -EINVAL;
> 
> This must be validated at the time of request_validate. We can't fail at
> this stage anymore.

After the modification about checking the required buffers in
req_validate(), we got failed in the following testRequests()
of V4L2 compliance test. The V4L2 compliance test case doesn't know
which buffers of the video devices are required and expects that the
MEDIA_REQUEST_IOC_QUEUE succeed when the request has any valid buffer.

For example, when the request has MDP 0 buffer only, the DIP's
req_validate() should return an error since it also need a buffer
from RAW video device, but it make compliance test get failed.

May I still check the required buffers in req_validate() in the next
patch? I will add some note to explain that the compliance test failed
item is related to the limitation?

=======================================================
int testRequests(struct node *node, bool test_streaming)
// ......
if (i)
	fail_on_test(!buf.qbuf(node));
buf.s_flags(buf.g_flags() | V4L2_BUF_FLAG_REQUEST_FD);
buf.s_request_fd(buf_req_fds[i]);
buf.s_field(V4L2_FIELD_ANY);
fail_on_test(buf.qbuf(node));
if (v4l_type_is_video(buf.g_type()) && v4l_type_is_output(buf.g_type()))
	fail_on_test(buf.g_field() == V4L2_FIELD_ANY);
fail_on_test(buf.querybuf(node, i));

// ......

// LINE 1807 in v4l2-test-buffers.cpp, we will got the  failed here.
// Since we need one RAW and one MDP0 buffer at least.
// v4l2-test-buffers.cpp(1807): doioctl_fd(buf_req_fds[i],
// MEDIA_REQUEST_IOC_QUEUE, 0)
//	test Requests: FAIL
fail_on_test(doioctl_fd(buf_req_fds[i], MEDIA_REQUEST_IOC_QUEUE, 0));
=======================================================

> > +
> > +static int mtk_dip_vb2_queue_setup(struct vb2_queue *vq,
> > +                                  unsigned int *num_buffers,
> > +                                  unsigned int *num_planes,
> > +                                  unsigned int sizes[],
> > +                                  struct device *alloc_devs[])
> > +{
> > +       struct mtk_dip_pipe *dip_pipe = vb2_get_drv_priv(vq);
> > +       struct mtk_dip_video_device *node =
> > +               mtk_dip_vbq_to_node(vq);
> > +       struct device *dev = &dip_pipe->dip_dev->pdev->dev;
> > +       struct device *buf_alloc_ctx;
> > +

[snip]

> > +
> > +       if (vq->type == V4L2_BUF_TYPE_META_CAPTURE ||
> > +           vq->type == V4L2_BUF_TYPE_META_OUTPUT)
> > +               size = fmt->fmt.meta.buffersize;
> > +       else
> > +               size = fmt->fmt.pix_mp.plane_fmt[0].sizeimage;
> > +
> > +       if (*num_planes) {
> > +               if (sizes[0] < size) {
> > +                       dev_dbg(dev, "%s:%s:%s: size error(user:%d, max:%d)\n",
> > +                               __func__, dip_pipe->desc->name,
> > +                               node->desc->name, sizes[0], size);
> > +                       return -EINVAL;
> > +               }
> 
> I don't think this is an error. This is for handling VIDIOC_CREATE_BUFS,
> which can allocate for any arbitrary format.
> 
> Whether the size of the buffer is big enough for current format should be
> checked in .buf_prepare callback.

When executing V4L2 compliance test, we need to check this image size to
pass the following q.create_bufs() test (LINE:709,
v4l2-test-buffers.cpp).

========================================================
node->g_fmt(fmt, q.g_type());
//.... 
fmt.s_height(fmt.g_height() / 2);
for (unsigned p = 0; p < fmt.g_num_planes(); p++)
	fmt.s_sizeimage(fmt.g_sizeimage(p) / 2, p);

// LINE 709 in v4l2-test-buffers.cpp
// It seems that the driver needs to return EINVAL when the buffer 
//size is smaller than the sizeimage required
	fail_on_test(q.create_bufs(node, 1, &fmt) != EINVAL);
========================================================

The kernel document has some similar description on VIDIOC_CREATE_BUFS. 

https://www.kernel.org/doc/html/latest/media/uapi/v4l/vidioc-create-bufs.html

=======================================================
Usually if the format.pix.sizeimage field is less than the minimum
required for the given format, then an error will be returned since
drivers will typically not allow this.
=======================================================

Should we check the image size of each plane here so that we can pass
the test?

> 
> > +       } else {
> > +               *num_planes = 1;
> > +               sizes[0] = size;
> > +       }
> > +
> > +       dev_dbg(dev, "%s:%s:%s: n_planes(%d), n_bufs(%d), size(%d)\n",
> > +               __func__, dip_pipe->desc->name,
> > +               node->desc->name, *num_planes, *num_buffers, sizes[0]);
> > +
> > +       return 0;
> > +}
> > +


Sincerely,

Frederic Chen