linux-kernel - Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: use helper to lookup panel-id

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Date:   Sun, 30 Jun 2019 15:04:51 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        aarch64-laptops@...ts.linaro.org,
        Rob Clark <robdclark@...omium.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] drm/bridge: ti-sn65dsi86: use helper to lookup panel-id

On Sun, Jun 30, 2019 at 2:58 PM Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Rob,
>
> On Sun, Jun 30, 2019 at 02:50:59PM -0700, Rob Clark wrote:
> > On Sun, Jun 30, 2019 at 2:17 PM Laurent Pinchart wrote:
> > > On Sun, Jun 30, 2019 at 01:36:08PM -0700, Rob Clark wrote:
> > > > From: Rob Clark <robdclark@...omium.org>
> > > >
> > > > Use the drm_of_find_panel_id() helper to decide which endpoint to use
> > > > when looking up panel.  This way we can support devices that have
> > > > multiple possible panels, such as the aarch64 laptops.
> > > >
> > > > Signed-off-by: Rob Clark <robdclark@...omium.org>
> > > > ---
> > > >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 5 +++--
> > > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > index 2719d9c0864b..56c66a43f1a6 100644
> > > > --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> > > > @@ -790,7 +790,7 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
> > > >                             const struct i2c_device_id *id)
> > > >  {
> > > >       struct ti_sn_bridge *pdata;
> > > > -     int ret;
> > > > +     int ret, panel_id;
> > > >
> > > >       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> > > >               DRM_ERROR("device doesn't support I2C\n");
> > > > @@ -811,7 +811,8 @@ static int ti_sn_bridge_probe(struct i2c_client *client,
> > > >
> > > >       pdata->dev = &client->dev;
> > > >
> > > > -     ret = drm_of_find_panel_or_bridge(pdata->dev->of_node, 1, 0,
> > > > +     panel_id = drm_of_find_panel_id();
> > > > +     ret = drm_of_find_panel_or_bridge(pdata->dev->of_node, 1, panel_id,
> > > >                                         &pdata->panel, NULL);
> > > >       if (ret) {
> > > >               DRM_ERROR("could not find any panel node\n");
> > >
> > > No, I'm sorry, but that's a no-go. We can't patch every single bridge
> > > driver to support this hack. We need a solution implemented at another
> > > level that will not spread throughout the whole subsystem.
> >
> > it could be possible to make a better helper.. but really there aren't
> > *that* many bridge drivers
> >
> > suggestions ofc welcome, but I think one way or another we are going
> > to need to patch bridges by the time we get to adding ACPI support, so
> > really trivial couple line patches to the handful of bridges we have
> > isn't really something that worries me
>
> It's only one right now as that's the only one you care about, but
> before we'll have time to blink, it will be another one, and another
> one, ... Sorry, that's a no-go for me.

I could ofc add helper call to all the existing bridges.. that seemed
a bit overkill for v1 patchset

BR,
-R