Re: [RFC PATCH V2 4/4] platform: mtk-isp: Add Mediatek FD driver

Tomasz Figa
2019-08-26T06:44:32Z

Hi Jerry,

On Sun, Aug 25, 2019 at 6:18 PM Jerry-ch Chen
<Jerry-ch.Chen@mediatek.com> wrote:
>
> Hi Tomasz,
>
> On Fri, 2019-08-02 at 16:28 +0800, Tomasz Figa wrote:
> > Hi Jerry,
> >
> > On Tue, Jul 09, 2019 at 04:41:12PM +0800, Jerry-ch Chen wrote:
> > > From: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> > >
> > > This patch adds the driver of Face Detection (FD) unit in
> > > Mediatek camera system, providing face detection function.
> > >
> > > The mtk-isp directory will contain drivers for multiple IP
> > > blocks found in Mediatek ISP system. It will include ISP Pass 1
> > > driver (CAM), sensor interface driver, DIP driver and face
> > > detection driver.
> > >
> > > Signed-off-by: Jerry-ch Chen <jerry-ch.chen@mediatek.com>
> > > ---
> > > drivers/media/platform/Makefile | 2 +
> > > drivers/media/platform/mtk-isp/fd/Makefile | 5 +
> > > drivers/media/platform/mtk-isp/fd/mtk_fd.h | 157 +++
> > > drivers/media/platform/mtk-isp/fd/mtk_fd_40.c | 1259 +++++++++++++++++++++++++
> > > include/uapi/linux/v4l2-controls.h | 4 +
> > > 5 files changed, 1427 insertions(+)
> > > create mode 100644 drivers/media/platform/mtk-isp/fd/Makefile
> > > create mode 100644 drivers/media/platform/mtk-isp/fd/mtk_fd.h
> > > create mode 100644 drivers/media/platform/mtk-isp/fd/mtk_fd_40.c
> > >
> >
> > Thanks for the patch! I finally got a chance to fully review the code. Sorry
> > for the delay. Please check my comments inline.
> >
> I appreciate your comments.
> I've fixed most of the comments and verifying them,
> Sorry for the delay, here is the reply.
>

Thanks for replying to all the comments, it's very helpful. I'll snip
the parts that I don't have any further comments.

[snip]

> > > + if (usercount == 1) {
> > > + pm_runtime_get_sync(&fd_dev->pdev->dev);
> > > + if (mtk_fd_hw_enable(fd_hw)) {
> > > + pm_runtime_put_sync(&fd_dev->pdev->dev);
> > > + atomic_dec_return(&fd_hw->fd_user_cnt);
> > > + mutex_unlock(&fd_hw->fd_hw_lock);
> > > + return -EINVAL;
> > > + }
> > > + }
> >
> > This is a simple mem-to-mem device, so there is no reason to keep it active
> > all the time it's streaming. Please just get the runtime PM counter when
> > queuing a job to the hardware and release it when the job finishes.
> >
> > I guess we might still want to do the costly operations like rproc_boot()
> > when we start streaming, though.
> >
> Do you mean by moving the pm_runtime_get/put stuff to the job execution
> and job finish place?

Yes.

> the rproc_boot() operation will be done here.
>

How much time does the rproc_boot() operation take?

[snip]

> > > +
> > > + pm_runtime_put_sync(&fd_dev->pdev->dev);
> >
> > Any reason to use pm_runtime_put_sync() over pm_runtime_put()?
> >
> No special reason to do so, the pm_runtime_put_sync here will be moved
> to the place each job finished.
>

If there is no reason, then the _sync() variant shouldn't be used, as
it could affect the performance negatively.

[snip]

> > > +static int mtk_fd_hw_job_exec(struct mtk_fd_hw *fd_hw,
> > > + struct fd_hw_param *fd_param,
> > > + void *output_vaddr)
> > > +{
> > > + struct fd_user_output *fd_output;
> > > + struct ipi_message fd_ipi_msg;
> > > + int ret;
> > > + u32 num;
> > > +
> > > + if (fd_param->user_param.src_img_fmt == FMT_UNKNOWN)
> > > + goto param_err;
> >
> > Is this possible?
> >
> Only if user set wrong format, I will remove this.
>

It shouldn't be possible to set a wrong format, because TRY_/S_FMT
should adjust what the user set to something that is valid.

> > > +
> > > + mutex_lock(&fd_hw->fd_hw_lock);
> > > + fd_hw->state = FD_ENQ;
> >
> > What is this state for?
> >
> It was for checking status, if a job is processing, the state is
> FD_ENQ,
> then we should wait for the last job to be done when pm_suspend().
>

If so, would it be possible to make it a bool and call is_processing?

[snip]

> > > +static int mtk_fd_vb2_queue_setup(struct vb2_queue *vq,
> > > + unsigned int *num_buffers,
> > > + unsigned int *num_planes,
> > > + unsigned int sizes[],
> > > + struct device *alloc_devs[])
> > > +{
> > > + struct mtk_fd_ctx *ctx = vb2_get_drv_priv(vq);
> > > + struct device *dev = ctx->dev;
> > > + unsigned int size;
> > > +
> > > + switch (vq->type) {
> > > + case V4L2_BUF_TYPE_META_CAPTURE:
> > > + size = ctx->dst_fmt.buffersize;
> > > + break;
> > > + case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
> > > + size = ctx->src_fmt.plane_fmt[0].sizeimage;
> > > + break;
> > > + default:
> > > + dev_err(dev, "invalid queue type: %d\n", vq->type);
> >
> > We should need to handle this.
> >
> Do you mean by giving a size instead of return -EINVAL?
>

Sorry, typo. I meant we shouldn't need to handle it, because we can't
get any other queue type here.

[snip]

> > > +static void mtk_fd_vb2_stop_streaming(struct vb2_queue *vq)
> > > +{
> > > + struct mtk_fd_ctx *ctx = vb2_get_drv_priv(vq);
> > > + struct vb2_buffer *vb;
> >
> > How do we guarantee here that the hardware isn't still accessing the buffers
> > removed below?
> >
> Maybe we can check the driver state flag and aborting the unfinished
> jobs?
> (fd_hw->state == FD_ENQ)
>

Yes, we need to either cancel or wait for the currently processing
job. It depends on hardware capabilities, but cancelling is generally
preferred for the lower latency.

> > > +
> > > + if (V4L2_TYPE_IS_OUTPUT(vq->type))
> > > + vb = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
> > > + else
> > > + vb = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
> > > +
> > > + while (vb) {
> > > + v4l2_m2m_buf_done(to_vb2_v4l2_buffer(vb), VB2_BUF_STATE_ERROR);
> > > + if (V4L2_TYPE_IS_OUTPUT(vq->type))
> > > + vb = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
> > > + else
> > > + vb = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
> > > + }
> >
> > We can use v4l2_m2m_buf_remove(). Also we can move the call into the loop
> > condition:
> >
> > while ((vb == v4l2_m2m_buf_remove(...)))
> > v4l2_m2m_buf_done(...);
> >
> Ok, I will refine as following:
>
> while ((vb = v4l2_m2m_buf_remove(V4L2_TYPE_IS_OUTPUT(vq->type)?
> &m2m_ctx->out_q_ctx :
> &m2m_ctx->cap_q_ctx)))
> v4l2_m2m_buf_done(vb, VB2_BUF_STATE_ERROR);

Please move the queue type check before the loop and save the queue
context in a local variable.

[snip]

> > > +}
> > > +
> > > +static void mtk_fd_vb2_request_complete(struct vb2_buffer *vb)
> > > +{
> > > + struct mtk_fd_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
> > > +
> > > + v4l2_ctrl_request_complete(vb->req_obj.req, &ctx->hdl);
> > > +}
> > > +
> > > +static void mtk_fd_fill_pixfmt_mp(struct v4l2_pix_format_mplane *dfmt,
> > > + const struct v4l2_pix_format_mplane *sfmt)
> > > +{
> > > + dfmt->width = sfmt->width;
> > > + dfmt->height = sfmt->height;
> > > + dfmt->pixelformat = sfmt->pixelformat;
> > > + dfmt->field = sfmt->field;
> > > + dfmt->colorspace = sfmt->colorspace;
> > > + dfmt->num_planes = sfmt->num_planes;
> > > +
> > > + /* Use default */
> > > + dfmt->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> > > + dfmt->quantization = V4L2_QUANTIZATION_DEFAULT;
> > > + dfmt->xfer_func =
> > > + V4L2_MAP_XFER_FUNC_DEFAULT(dfmt->colorspace);
> > > + dfmt->plane_fmt[0].bytesperline = dfmt->width * 2;
> > > + dfmt->plane_fmt[0].sizeimage =
> > > + dfmt->height * dfmt->plane_fmt[0].bytesperline;
> > > + memset(dfmt->reserved, 0, sizeof(dfmt->reserved));
> > > +}
> >
> > Could we unify this function with mtk_fd_m2m_try_fmt_out_mp()? That function
> > should be almost directly reusable for the default format initialization +/-
> > the arguments passed to it.
> >
> Ok, I will try to reuse it as following:
>
> static void mtk_fd_fill_pixfmt_mp(struct v4l2_pix_format_mplane *dfmt,
> const struct v4l2_pix_format_mplane *sfmt)
> {
> dfmt->field = V4L2_FIELD_NONE;
> dfmt->colorspace = V4L2_COLORSPACE_BT2020;
> dfmt->num_planes = sfmt->num_planes;
> dfmt->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> dfmt->quantization = V4L2_QUANTIZATION_DEFAULT;
> dfmt->xfer_func =
> V4L2_MAP_XFER_FUNC_DEFAULT(dfmt->colorspace);
>
> /* Keep user setting as possible */
> dfmt->width = clamp(dfmt->width,
> MTK_FD_OUTPUT_MIN_WIDTH,
> MTK_FD_OUTPUT_MAX_WIDTH);
> dfmt->height = clamp(dfmt->height,
> MTK_FD_OUTPUT_MIN_HEIGHT,
> MTK_FD_OUTPUT_MAX_HEIGHT);
>
> if (sfmt->num_planes == 2) {
> /* NV16M and NV61M has 1 byte per pixel */
> dfmt->plane_fmt[0].bytesperline = dfmt->width;
> dfmt->plane_fmt[1].bytesperline = dfmt->width;
> } else {
> /* 2 bytes per pixel */
> dfmt->plane_fmt[0].bytesperline = dfmt->width * 2;
> }
>
> dfmt->plane_fmt[0].sizeimage =
> dfmt->height * dfmt->plane_fmt[0].bytesperline;
> }

How would the implementation of TRY_FMT look in this case?

[snip]

> > > +static int mtk_fd_m2m_enum_fmt_out_mp(struct file *file, void *fh,
> > > + struct v4l2_fmtdesc *f)
> > > +{
> > > + int i;
> > > +
> > > + for (i = 0; i < NUM_FORMATS; ++i) {
> > > + if (i == f->index) {
> > > + f->pixelformat = in_img_fmts[i].pixelformat;
> > > + return 0;
> > > + }
> > > + }
> >
> > Why don't we just check if f->index is within the [0, ARRAY_SIZE()-1] bounds
> > and then just use it to index the array directly?
> >
> I will refine as :
>
> static int mtk_fd_m2m_enum_fmt_out_mp(struct file *file, void *fh,
> struct v4l2_fmtdesc *f)
> {
> if ((f->index >= 0) && (f->index < NUM_FORMATS)) {

f->index is unsigned

> f->pixelformat = in_img_fmts[f->index].pixelformat;
> return 0;
> }
>
> return -EINVAL;
> }

nit: The usual convention is to check for invalid values and return early, i.e.

if (f->index >= NUM_FORMATS)
return -EINVAL;

f->pixelformat = in_img_fmts[f->index].pixelformat;
return 0;

> > > +
> > > + return -EINVAL;
> > > +}
> > > +
> > > +static int mtk_fd_m2m_try_fmt_out_mp(struct file *file,
> > > + void *fh,
> > > + struct v4l2_format *f)
> >
> > I think we could just shorten the function prefixes to "mtk_fd_".
> >
> Do you mean by replace mtk_fd_m2m_* with mtk_fd_ ?
>

Yes.

[snip]

> > > +static int mtk_fd_request_validate(struct media_request *req)
> > > +{
> > > + unsigned int count;
> > > +
> > > + count = vb2_request_buffer_cnt(req);
> > > + if (!count)
> > > + return -ENOENT;
> >
> > Why -ENOENT?
> >
> Reference the return code in vb2_request_validate()

You're right, -ENOENT seems to be the right error code here.

> I consider refining as following:
> static int mtk_fd_request_validate(struct media_request *req)
> {
> if (vb2_request_buffer_cnt(req) > 1)
> return -EINVAL;
>
> return vb2_request_validate(req);
> }
> or maybe I don't need to worry the request count greater than 1,
> just remove this function and set vb2_request_validate as .req_validate
> directly?
>

Given that we only have 1 queue handling requests, we should be able
to just use vb2_request_validate() indeed.

Best regards,
Tomasz