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

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

Hi Tomasz,


On Tue, 2019-06-11 at 17:59 +0900, Tomasz Figa wrote:
> On Tue, Jun 11, 2019 at 5:48 PM Frederic Chen
> <frederic.chen@mediatek.com> wrote:
> >
> > Dear Tomasz,
> >
> > I'd like to elaborate more about the tuning_data.va.
> > Would you like to give us some advice about our improvement proposal inline?
> >
> > Thank you very much.
> >
> >
> > On Wed, 2019-05-22 at 03:14 +0800, Frederic Chen wrote:
> > > Dear Tomasz,
> > >
> > > I appreciate your comment. It is very helpful for us.
> > >
> > >
> > > > > diff --git a/drivers/media/platform/mtk-isp/isp_50/dip/mtk_dip-sys.c b/drivers/media/platform/mtk-isp/isp_50/dip/mtk_dip-sys.c
> > > > > new file mode 100644
> > > > > index 000000000000..54d2b5f5b802
> > > > > --- /dev/null
> > > > > +++ b/drivers/media/platform/mtk-isp/isp_50/dip/mtk_dip-sys.c
> > > > > @@ -0,0 +1,1384 @@
> >
> > [snip]
> >
> > > > > +static void dip_submit_worker(struct work_struct *work)
> > > > > +{
> > > > > +       struct mtk_dip_hw_submit_work *dip_submit_work =
> > > > > +               container_of(work, struct mtk_dip_hw_submit_work, frame_work);
> > > > > +       struct mtk_dip_hw *dip_hw = dip_submit_work->dip_hw;
> > > > > +       struct mtk_dip_dev *dip_dev = mtk_dip_hw_to_dev(dip_hw);
> > > > > +       struct mtk_dip_hw_work *dip_work;
> > > > > +       struct mtk_dip_hw_subframe *buf;
> > > > > +       u32 len, num;
> > > > > +       int ret;
> > > > > +
> > > > > +       num  = atomic_read(&dip_hw->num_composing);
> > > > > +
> > > > > +       mutex_lock(&dip_hw->dip_worklist.queuelock);
> > > > > +       dip_work = list_first_entry(&dip_hw->dip_worklist.queue,
> >
> > [snip]
> >
> > > > > +
> > > > > +       if (dip_work->frameparams.tuning_data.pa == 0) {
> > > > > +               dev_dbg(&dip_dev->pdev->dev,
> > > > > +                       "%s: frame_no(%d) has no tuning_data\n",
> > > > > +                       __func__, dip_work->frameparams.frame_no);
> > > > > +
> > > > > +               memcpy(&dip_work->frameparams.tuning_data,
> > > > > +                      &buf->tuning_buf, sizeof(buf->tuning_buf));
> > > >
> > > > Ditto.
> > > >
> > >
> > > I got it.
> > >
> > > > > +               memset((char *)buf->tuning_buf.va, 0, DIP_TUNING_SZ);
> > > >
> > > > Ditto.
> > >
> > > I got it.
> > >
> > > >
> > > > > +               /*
> > > > > +                * When user enqueued without tuning buffer,
> > > > > +                * it would use driver internal buffer.
> > > > > +                * So, tuning_data.va should be 0
> > > > > +                */
> > > > > +               dip_work->frameparams.tuning_data.va = 0;
> > > >
> > > > I don't understand this. We just zeroed the buffer via this kernel VA few
> > > > lines above, so why would it have to be set to 0?
> > > >
> > >
> > > I will remove this unnecessary line.
> > >
> > > > > +       }
> >
> > After confirming the firmware part, I found that we use this field
> > (tuning_data.va) to notify firmware if there is no tuning data from
> > user.
> >
> > - frameparams.tuning_data.va is 0: use the default tuning data in
> >                                    SCP, but we still need to pass
> >                                    frameparams.tuning_data.pa because
> >                                    the buffer contains some working
> >                                    buffer required.
> > - frameparams.tuning_data.va is not 0: the tuning data was passed from
> >                                        the user
> >
> > Since we should not pass cpu addres to SCP, could I rename tuning_data.va
> > as tuning_data.cookie, and write a constant value to indicate if SCP
> > should use its internal default setting or not here?
> >
> > For example,
> > /* SCP uses tuning data passed from userspace*/
> > dip_work->frameparams.tuning_data.cookie = MTK_DIP_USER_TUNING_DATA;
> >
> > /* SCP uses internal tuning data */
> > dip_work->frameparams.tuning_data.cookie = MTK_DIP_DEFAULT_TUNING_DATA;
> 
> Perhaps we could just call it "present" and set to true or false?
> 

Yes. I would like to use "present" here.

Original:
  struct img_addr {
      u64 va; /* Used by Linux OS access */
      u32 pa; /* Used by CM4 access */
      u32 iova; /* Used by IOMMU HW access */
  } __attribute__ ((__packed__));

  struct img_ipi_frameparam {
      u32 index;
      u32 frame_no;
      u64 timestamp;
      u8 type;	/* enum mdp_stream_type */
      u8 state;
      u8 num_inputs;
      u8 num_outputs;
      u64 drv_data;
      struct img_input inputs[IMG_MAX_HW_INPUTS];
      struct img_output	outputs[IMG_MAX_HW_OUTPUTS];
      struct img_addr tuning_data;
      struct img_addr subfrm_data;
      struct img_sw_addr config_data;
      struct img_sw_addr self_data;
  } __attribute__ ((__packed__));


Modified:
  struct tuning_buf {
      u8 present;
      u32 pa;	/* Used by CM4 access */
      u32 iova;	/* Used by IOMMU HW access */
  } __attribute__ ((__packed__));
	
  struct img_ipi_frameparam {
      /* ... */
      struct tuning_buf	tuning_data;
      /* ... */
  } __attribute__ ((__packed__));


> Best regards,
> Tomasz


Sincerely,

Frederic Chen