linux-kernel - Re: [PATCH] drm/bridge: dw-mipi-dsi: Move drm_bridge

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Date:   Wed, 24 Feb 2021 22:31:19 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     yannick Fertre <yannick.fertre@...s.st.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Heiko Stubner <heiko@...ech.de>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Sandy Huang <hjc@...k-chips.com>,
        Yannick Fertre <yannick.fertre@...com>,
        Philippe Cornu <philippe.cornu@...com>,
        Marek Vasut <marex@...x.de>,
        Vincent Abriou <vincent.abriou@...com>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonas Karlman <jonas@...boo.se>,
        Sam Ravnborg <sam@...nborg.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-amarula <linux-amarula@...rulasolutions.com>
Subject: Re: [PATCH] drm/bridge: dw-mipi-dsi: Move drm_bridge_add into probe

Hi Yannick,

Thanks for testing this change.

On Mon, Feb 15, 2021 at 1:39 PM yannick Fertre
<yannick.fertre@...s.st.com> wrote:
>
> Hello Jagan, I tested your patch on the stm32mp1 board.
> Unfortunately, the dsi panel does not probe well with this patch. The
> problem is due to the panel which is placed in the node of the dsi
> bridge (no problem with i2c devices).
>
> Regarding component bindings for stm drivers, I am currently working on
> a new version.

1. All non-I2C bridges are attaching dsi via mipi_dsi_attach during
the bridge controller probe and that would be expecting
panel_or_bridge need to be in DSI host attach.

2. I2C bridges are attaching dsi via mipi_dsi_attach during the bridge
attach function and that would be expecting panel_or_bridge need to be
in DSI probe.

I believe these types of DSI controllers followed by DSI panels,
bridges are not available in Mainline. if I'm not mistaken.

Adding component bindings in this regards never helps, this seems to
be common for component or non-components DSI host drivers.

One way to handle this issue can be during drm helper initialization,
like attaching the dsi host instead of calling directly from bridge or
panel drivers.

Laurent, Heiko - let me know your suggestions if it make sense, thanks.

Jagan.