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Date:   Mon, 28 Mar 2022 19:10:04 +0800
From:   Xin Ji <xji@analogixsemi.com>
To:     Robert Foss <robert.foss@linaro.org>
Cc:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        =?iso-8859-1?Q?N=EDcolas_F=2E_R=2E_A=2E?= Prado 
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        devicetree@vger.kernel.org, Chen-Yu Tsai <wenst@chromium.org>
Subject: Re: [PATCH v12 3/4] drm/bridge: anx7625: add MIPI DPI input feature
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On Mon, Mar 28, 2022 at 11:54:12AM +0200, Robert Foss wrote:
> > > > > > > -   DRM_DEV_DEBUG_DRIVER(dev, "found dsi host node.\n");
> > > > > > > +   bus_type = V4L2_FWNODE_BUS_TYPE_PARALLEL;
> > > > > > > +   mipi_lanes = MAX_LANES_SUPPORT;
> > > > > > > +   ep0 = of_graph_get_endpoint_by_regs(np, 0, 0);
> > > > > > > +   if (ep0) {
> > > > > > > +           if (of_property_read_u32(ep0, "bus-type", &bus_type))
> > > > > > > +                   bus_type = 0;
> > > > > > > +
> > > > > > > +           mipi_lanes = of_property_count_u32_elems(ep0, "data-lanes");
> > > > > > > +   }
> > > > > > > +
> > > > > > > +   if (bus_type == V4L2_FWNODE_BUS_TYPE_PARALLEL) /* bus type is Parallel(DSI) */
> > > > > >
> > > > > > This is not correct *at all*. V4L2_FWNODE_BUS_TYPE_PARALLEL has nothing
> > > > > > to do with DSI. DSI stands for Digital *Serial* Interface. If anything,
> > > > > > the V4L2_FWNODE_BUS_TYPE_PARALLEL type would map better to DPI, even if
> > > > > > it's not an exact match.
> > > > > >
> > > > > > This patch has landed in v5.17-rc1, along with the corresponding
> > > > > > bindings. As DT bindings are an ABI, we should really fix this before
> > > > > > v5.17 is released. There is no DSI bus types defined in DT, and adding
> > > > > > one as a fix so late in the v5.17-rc cycle seems a bit of a stretch to
> > > > > > me (unless Rob disagrees).
> > > > > >
> > > > > > It would seem best to revert this series and the corresponding bindings,
> > > > > > and retry in v5.18.
> > > > >
> > > > > There is a DT patch using this property that is already queued up for 5.17
> > > > > in the soc tree:
> > > > >
> > > > > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fall%2F20220214200507.2500693-1-nfraprado%40collabora.com%2F&amp;data=04%7C01%7Cxji%40analogixsemi.com%7C450c5609d8c24e9a34fa08da10a0f126%7Cb099b0b4f26c4cf59a0fd5be9acab205%7C0%7C0%7C637840580680816692%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=bARYbwXq6IJGxn3UBp%2F75lZhoTpzmZkTQsN0yvs7Cgg%3D&amp;reserved=0
> > > > >
> > > > > merged here:
> > > > >
> > > > > https://nam10.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgit.kernel.org%2Fsoc%2Fsoc%2Fc%2F32568ae37596b529628ac09b875f4874e614f63f&amp;data=04%7C01%7Cxji%40analogixsemi.com%7C450c5609d8c24e9a34fa08da10a0f126%7Cb099b0b4f26c4cf59a0fd5be9acab205%7C0%7C0%7C637840580680816692%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=lt3Tp8DveE1RJ%2F1MqDzYdKtHDxIyqhBbur%2Fm4N432AI%3D&amp;reserved=0
> > > > >
> > > > > We will need to revert that one as well.
> > > >
> > > > I just submitted a series reverting the dt-binding change + the
> > > > related commit to "mt8183: jacuzzi".
> > > > Can I get a quick r-b/a-b in order to get this into v5.17.
> > > >
> > > > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fall%2F20220307154558.2505734-3-robert.foss%40linaro.org%2F&amp;data=04%7C01%7Cxji%40analogixsemi.com%7C450c5609d8c24e9a34fa08da10a0f126%7Cb099b0b4f26c4cf59a0fd5be9acab205%7C0%7C0%7C637840580680816692%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=dgA%2BrQ3KBMPLoR5bwL5Wt2Vs6EuNy%2Fh9yfOftxeUXjM%3D&amp;reserved=0
> > > >
> > >
> > > v2 of revert submitted.
> > >
> > > https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fall%2F20220308094911.2680291-1-robert.foss%40linaro.org%2F&amp;data=04%7C01%7Cxji%40analogixsemi.com%7C450c5609d8c24e9a34fa08da10a0f126%7Cb099b0b4f26c4cf59a0fd5be9acab205%7C0%7C0%7C637840580680816692%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=vIcCvXrwZs8XhXuoQ8On7vB9%2Bwrsov1DD5UBX%2B1G93Q%3D&amp;reserved=0
> > >
> > > Xin: Will you spin a series that adds DPI support and re-enables DPI
> > > for anx7625? Additionally, "mt8183: jacuzzi" will have to have DPI
> > > re-enabled.
> > Hi Robert Foss, I'm little confused, do I need resend this serial or
> > send a patch based on currently define(V4L2_FWNODE_BUS_TYPE_PARALLEL)?
> >
> > And use V4L2_FWNODE_BUS_TYPE_PARALLEL for DPI, other value for DSI
> > setup?
> 
> V4L2_FWNODE_BUS_TYPE_PARALLEL is not meant to be used for DPI, but
> rather is used to represtent CPI. So another enum (something along the
> lines of V4L2_FWNODE_BUS_TYPE_DPI) needs to be defined, and then this
> series needs to use this new enum.
> 
> I'd like to see the following:
>  - Introduction of V4L2_FWNODE_BUS_TYPE_DPI
>  - Reworking this series to use V4L2_FWNODE_BUS_TYPE_DPI
>  - Reworking "mt8183: jacuzzi" to use V4L2_FWNODE_BUS_TYPE_DPI
> 
> Does that make sense?
Hi Rob, OK, I'll prepare the patch for review.
Thanks,
Xin
> 
> 
> Rob.