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

Tomasz Figa
2019-09-03T05:20:00Z

On Mon, Sep 2, 2019 at 8:47 PM Jerry-ch Chen <Jerry-ch.Chen@mediatek.com> wrote:
>
> Hi Tomasz,
>
> On Fri, 2019-08-30 at 16:33 +0800, Tomasz Figa wrote:
> > On Wed, Aug 28, 2019 at 11:00 AM Jerry-ch Chen
> > <Jerry-ch.Chen@mediatek.com> wrote:
> > >
> > > Hi Tomasz,
> > >
> > > On Mon, 2019-08-26 at 14:36 +0800, Tomasz Figa wrote:
> > > > 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:
[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[2];
> > >
> > > switch (vq->type) {
> > > case V4L2_BUF_TYPE_META_CAPTURE:
> > > size[0] = ctx->dst_fmt.buffersize;
> > > break;
> > > case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
> > > size[0] = ctx->src_fmt.plane_fmt[0].sizeimage;
> > > if (*num_planes == 2)
> > > size[1] = ctx->src_fmt.plane_fmt[1].sizeimage;
> > > break;
> > > }
> > >
> > > if (*num_planes == 1) {
> > > if (sizes[0] < size[0])
> > > return -EINVAL;
> > > } else if (*num_planes == 2) {
> > > if ((sizes[0] < size[0]) && (sizes[1] < size[1]))
> > > return -EINVAL;
> >
> > Can we just use a loop here and combine the 2 cases above?
> >
> > Also, we need to fail with -EINVAL if *num_planes is > 2.
> >
> > > } else {
> > > *num_planes = 1;
> > > sizes[0] = size[0];
> >
> > This should be the case if *num_planes == 0 and the number of planes
> > and sizes should match the currently active format.
> >
> I appreciate your comments,
>
> Ok, I will update as following:
> 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);
> unsigned int size[2];
> unsigned int plane;
>
> switch (vq->type) {
> case V4L2_BUF_TYPE_META_CAPTURE:
> size[0] = ctx->dst_fmt.buffersize;
> break;
> case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
> size[0] = ctx->src_fmt.plane_fmt[0].sizeimage;
> if (*num_planes == 2)
> size[1] = ctx->src_fmt.plane_fmt[1].sizeimage;
> break;
> }
>
> if (*num_planes > 2)
> return -EINVAL;
> if (*num_planes == 0) {
> if (vq->type == V4L2_BUF_TYPE_META_CAPTURE) {
> sizes[0] = ctx->dst_fmt.buffersize;
> *num_planes = 1;
> return 0;
> }
>
> *num_planes = ctx->src_fmt.num_planes;
> for (plane = 0; plane < *num_planes; plane++)
> sizes[plane] = ctx->src_fmt.plane_fmt[plane].sizeimage;
> return 0;
> }
>
> for (plane = 0; plane < *num_planes; plane++) {
> if(sizes[plane] < size[plane])
> return -EINVAL;
> }
> return 0;
> }
>

Looks good, thanks!

> > > }
> > >
> > > return 0;
> > > }
> > >
> > > > [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.
> > > >
> > > Ok, it the state is ENQ, then we can disable the FD hw by controlling
> > > the registers.
> > >
> > > for example:
> > > writel(0x0, fd->fd_base + FD_HW_ENABLE);
> > > writel(0x0, fd->fd_base + FD_INT_EN);
> > >
> >
> > What's exactly the effect of writing 0 to FD_HW_ENABLE?
> >
> Sorry, my last reply didn't solve the question,
> we should implement a mtk_fd_job_abort() for v4l2_m2m_ops().
>
> which is able to readl_poll_timeout_atomic()
> and check the HW busy bits in the register FD_INT_EN;
>
> if they are not cleared until timeout, we could handle the last
> processing job.
> Otherwise, the FD irq handler should have handled the last processing
> job and we could continue the stop_streaming().
>
> For job_abort():
> static void mtk_fd_job_abort(void *priv)
> {
> struct mtk_fd_ctx *ctx = priv;
> struct mtk_fd_dev *fd = ctx->fd_dev;
> u32 val;
> u32 ret;
>
> ret = readl_poll_timeout_atomic(fd->fd_base + MTK_FD_REG_OFFSET_INT_EN,
> val,
> (val & MTK_FD_HW_BUSY_MASK) ==
> MTK_FD_HW_STATE_IS_BUSY,
> USEC_PER_MSEC, MTK_FD_STOP_HW_TIMEOUT);

Hmm, would it be possible to avoid the busy wait by having a
completion that could be signalled from the interrupt handler?

Best regards,
Tomasz