linux-kernel - Re: [PATCH v12 3/4] drm/bridge: anx7625: add MIPI DPI input feature

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Date:   Mon, 7 Mar 2022 16:49:11 +0100
From:   Robert Foss <robert.foss@...aro.org>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, Xin Ji <xji@...logixsemi.com>,
        a.hajda@...sung.com, narmstrong@...libre.com,
        dan.carpenter@...cle.com, jonas@...boo.se,
        jernej.skrabec@...il.com, airlied@...ux.ie, daniel@...ll.ch,
        sam@...nborg.org, pihsun@...omium.org, tzungbi@...gle.com,
        maxime@...no.tech, drinkcat@...gle.com, hsinyi@...omium.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        bliang@...logixsemi.com, qwen@...logixsemi.com, robh+dt@...nel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v12 3/4] drm/bridge: anx7625: add MIPI DPI input feature

On Mon, 7 Mar 2022 at 07:12, Chen-Yu Tsai <wenst@...omium.org> wrote:
>
> On Sun, Mar 06, 2022 at 07:13:30PM +0200, Laurent Pinchart wrote:
> > Hello Xin,
> >
> > (Question for Rob below, and I'm afraid this is urgent as we need to
> > merge a fix in v5.17).
> >
> > On Fri, Nov 05, 2021 at 11:19:03AM +0800, Xin Ji wrote:
> > > The basic anx7625 driver only support MIPI DSI rx signal input.
> > > This patch add MIPI DPI rx input configuration support, after apply
> > > this patch, the driver can support DSI rx or DPI rx by adding
> > > 'bus-type' in DT.
> > >
> > > Reviewed-by: Robert Foss <robert.foss@...aro.org>
> > > Signed-off-by: Xin Ji <xji@...logixsemi.com>
> > > ---
> > >  drivers/gpu/drm/bridge/analogix/anx7625.c | 247 ++++++++++++++++------
> > >  drivers/gpu/drm/bridge/analogix/anx7625.h |  18 +-
> > >  2 files changed, 205 insertions(+), 60 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > index f48e91134c20..f7c3386c8929 100644
> > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
>
> [...]
>
> > >  static int anx7625_parse_dt(struct device *dev,
> > >                         struct anx7625_platform_data *pdata)
> > >  {
> > > -   struct device_node *np = dev->of_node;
> > > +   struct device_node *np = dev->of_node, *ep0;
> > >     struct drm_panel *panel;
> > >     int ret;
> > > +   int bus_type, mipi_lanes;
> > > +
> > > +   anx7625_get_swing_setting(dev, pdata);
> > >
> > > +   pdata->is_dpi = 1; /* default dpi mode */
> > >     pdata->mipi_host_node = of_graph_get_remote_node(np, 0, 0);
> > >     if (!pdata->mipi_host_node) {
> > >             DRM_DEV_ERROR(dev, "fail to get internal panel.\n");
> > >             return -ENODEV;
> > >     }
> > >
> > > -   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://lore.kernel.org/all/20220214200507.2500693-1-nfraprado@collabora.com/
>
> merged here:
>
> http://git.kernel.org/soc/soc/c/32568ae37596b529628ac09b875f4874e614f63f
>
> 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://lore.kernel.org/all/20220307154558.2505734-3-robert.foss@linaro.org/

>
> ChenYu