linux-kernel - Re: [PATCH v2] drm/bridge: adv7511: Attach to DSI host at probe time

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Message-ID: <CALAqxLVtzQSgVL0B0M2RNB_U-TvNs7+C=k6VUk0VJywdgJbNFQ@mail.gmail.com>
Date:   Tue, 27 Aug 2019 13:03:09 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Matt Redfearn <matt.redfearn@...nci.com>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matthew Redfearn <matthew.redfearn@...nci.com>,
        Sean Paul <seanpaul@...omium.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH v2] drm/bridge: adv7511: Attach to DSI host at probe time

On Mon, Aug 19, 2019 at 3:27 PM John Stultz <john.stultz@...aro.org> wrote:
> On Thu, Jun 27, 2019 at 8:18 AM Matt Redfearn <matt.redfearn@...nci.com> wrote:
> >
> > In contrast to all of the DSI panel drivers in drivers/gpu/drm/panel
> > which attach to the DSI host via mipi_dsi_attach() at probe time, the
> > ADV7533 bridge device does not. Instead it defers this to the point that
> > the upstream device connects to its bridge via drm_bridge_attach().
> > The generic Synopsys MIPI DSI host driver does not register it's own
> > drm_bridge until the MIPI DSI has attached. But it does not call
> > drm_bridge_attach() on the downstream device until the upstream device
> > has attached. This leads to a chicken and the egg failure and the DRM
> > pipeline does not complete.
> > Since all other mipi_dsi_device drivers call mipi_dsi_attach() in
> > probe(), make the adv7533 mipi_dsi_device do the same. This ensures that
> > the Synopsys MIPI DSI host registers it's bridge such that it is
> > available for the upstream device to connect to.
> >
> > Signed-off-by: Matt Redfearn <matt.redfearn@...nci.com>
> >
> > ---
>
> As a heads up, I just did some testing on drm-misc-next and this patch
> seems to be breaking the HiKey board.  On bootup, I'm seeing:
> [    4.209615] adv7511 2-0039: 2-0039 supply avdd not found, using
> dummy regulator
> [    4.217075] adv7511 2-0039: 2-0039 supply dvdd not found, using
> dummy regulator
> [    4.224453] adv7511 2-0039: 2-0039 supply pvdd not found, using
> dummy regulator
> [    4.231804] adv7511 2-0039: 2-0039 supply a2vdd not found, using
> dummy regulator
> [    4.239242] adv7511 2-0039: 2-0039 supply v3p3 not found, using
> dummy regulator
> [    4.246615] adv7511 2-0039: 2-0039 supply v1p2 not found, using
> dummy regulator
> [    4.272970] adv7511 2-0039: failed to find dsi host
>
> over and over.  The dummy regulator messages are normal, but usually
> [    4.444315] kirin-drm f4100000.ade: bound f4107800.dsi (ops dsi_ops)
>
> Starts up right afterward.

Hey Matt, Andrzej,
  I just wanted to follow up on this as this patch is breaking a
couple of boards. Any sense of what might be missing, or is this
something we should revert?

I'm happy to test any patch ideas you have.

thanks
-john