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Date:   Mon, 21 Jun 2021 18:05:17 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Marek Vasut <marex@denx.de>,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        Eric Anholt <eric@anholt.net>,
        Tim Gover <tim.gover@raspberrypi.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Andrzej Hajda <a.hajda@samsung.com>,
        bcm-kernel-feedback-list@broadcom.com,
        linux-rpi-kernel@lists.infradead.org,
        Phil Elwell <phil@raspberrypi.com>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] drm/vc4: dsi: Only register our component once a DSI
 device is attached
Message-ID: <20210621160517.5fptdj4tkbzgqn76@gilmour>
References: <20200707101912.571531-1-maxime@cerno.tech>
 <YM6dgVb12oITNfc0@pendragon.ideasonboard.com>
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Hi Laurent,

On Sun, Jun 20, 2021 at 04:44:33AM +0300, Laurent Pinchart wrote:
> Hi Maxime,
>=20
> I'm testing this, and I'm afraid it causes an issue with all the
> I2C-controlled bridges. I'm focussing on the newly merged ti-sn65dsi83
> driver at the moment, but other are affected the same way.
>=20
> With this patch, the DSI component is only added when the DSI device is
> attached to the host with mipi_dsi_attach(). In the ti-sn65dsi83 driver,
> this happens in the bridge attach callback, which is called when the
> bridge is attached by a call to drm_bridge_attach() in vc4_dsi_bind().
> This creates a circular dependency, and the DRM/KMS device is never
> created.

We discussed it on IRC, but it makes more sense here.

The thing is, that patch is fixing a circular dependency we discussed
with Andrzej a year ago:

https://lore.kernel.org/dri-devel/20200630132711.ezywhvoiuv3swo57@gilmour.l=
an/

It seems like we have to choose between having the panels or bridges
working :/

Maxime

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