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

Tomasz Figa
2019-06-11T08:59:36Z

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?

Best regards,
Tomasz