linux-kernel - Re: [PATCH v2 1/6] dt-bindings: drm/panel-simple: Introduce generic eDP panels

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Message-ID: <CAL_JsqKbZvQ_aXMMDUZL2sizy9LxJ-Z5Qw6WL-gOxBE8TCTyYA@mail.gmail.com>
Date:   Mon, 9 Aug 2021 16:56:28 -0600
From:   Rob Herring <robh@...nel.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Daniel Vetter <daniel@...ll.ch>,
        Thierry Reding <thierry.reding@...il.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Linus W <linus.walleij@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Steev Klimaszewski <steev@...i.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Subject: Re: [PATCH v2 1/6] dt-bindings: drm/panel-simple: Introduce generic
 eDP panels

On Mon, Aug 9, 2021 at 4:20 PM Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Mon, Aug 2, 2021 at 6:39 AM Rob Herring <robh@...nel.org> wrote:
> >
> > On Fri, 30 Jul 2021 14:26:20 -0700, Douglas Anderson wrote:
> > > eDP panels generally contain almost everything needed to control them
> > > in their EDID. This comes from their DP heritage were a computer needs
> > > to be able to properly control pretty much any DP display that's
> > > plugged into it.
> > >
> > > The one big issue with eDP panels and the reason that we need a panel
> > > driver for them is that the power sequencing can be different per
> > > panel.
> > >
> > > While it is true that eDP panel sequencing can be arbitrarily complex,
> > > in practice it turns out that many eDP panels are compatible with just
> > > some slightly different delays. See the contents of the bindings file
> > > introduced in this patch for some details.
> > >
> > > The fact that eDP panels are 99% probable and that the power
> > > sequencing (especially power up) can be compatible between many panels
> > > means that there's a constant desire to plug multiple different panels
> > > into the same board. This could be for second sourcing purposes or to
> > > support multiple SKUs (maybe a 11" and a 13", for instance).
> > >
> > > As discussed [1], it should be OK to support this by adding two
> > > properties to the device tree to specify the delays needed for
> > > powering up the panel the first time. We'll create a new "edp-panel"
> > > bindings file and define the two delays that might need to be
> > > specified. NOTE: in the vast majority of the cases (HPD is hooked up
> > > and isn't glitchy or is debounced) even these delays aren't needed.
> > >
> > > [1] https://lore.kernel.org/r/CAD=FV=VZYOMPwQZzWdhJGh5cjJWw_EcM-wQVEivZ-bdGXjPrEQ@mail.gmail.com
> > >
> > > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > > ---
> > >
> > > Changes in v2:
> > > - No longer allow fallback to panel-simple.
> > > - Add "-ms" suffix to delays.
> > >
> > >  .../bindings/display/panel/panel-edp.yaml     | 188 ++++++++++++++++++
> > >  1 file changed, 188 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/display/panel/panel-edp.yaml
> > >
> >
> > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> >
> > yamllint warnings/errors:
> >
> > dtschema/dtc warnings/errors:
> > /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/display/panel/panel-edp.example.dt.yaml: bridge@2d: 'aux-bus' does not match any of the regexes: 'pinctrl-[0-9]+'
> >         From schema: /builds/robherring/linux-dt-review/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
> > \ndoc reference errors (make refcheckdocs):
> >
> > See https://patchwork.ozlabs.org/patch/1511822
> >
> > This check can fail if there are any dependencies. The base for a patch
> > series is generally the most recent rc1.
>
> I think it's a dependency problem. No hits here:
>
> git grep aux-bus v5.14-rc5 -- Documentation/devicetree/bindings/
>
> ...but I get hits against "linuxnext".

Am I supposed to figure them out? A simple "'aux-bus' warning is fixed
by commit XYZ in foo tree' in the patch would help. Then I won't send
the failure email (I do review them, so it's not your free testing
service :) ). If you list the dependency then I'm not going to spam
folks with failures. If you don't then I will so no one applies things
without dependencies (as often they are not queued).

> Rob: I'm hoping that this can
> still be in your queue for review even with the bot warning.

Sometimes, but you don't have to guess. You can look at patchwork.
Though there is a latency between sending failure emails and my
changing PW state.

In any case, it looks good to me.

Reviewed-by: Rob Herring <robh@...nel.org>

Rob