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Date:   Thu, 7 Oct 2021 12:16:27 +0200
From:   Andrzej Hajda <>
To:     Stephen Boyd <>,
        Greg Kroah-Hartman <>
        Arnd Bergmann <>,
        Benjamin Gaignard <>,
        Chen Feng <>,
        Chen-Yu Tsai <>,
        Christian Gmeiner <>,
        Chun-Kuang Hu <>,
        Daniel Vetter <>,
        Emma Anholt <>,
        Heiko Stübner <>,
        Inki Dae <>,
        James Qian Wang <>,
        Jaroslav Kysela <>,
        Joerg Roedel <>,
        John Stultz <>,
        Joonyoung Shim <>,
        Jyri Sarha <>,
        Kai Vehmanen <>,
        Kyungmin Park <>,
        Laurent Pinchart <>,,,, Liviu Dudau <>,
        Lucas Stach <>,
        Mark Brown <>,
        Maxime Ripard <>,
        Neil Armstrong <>,
        Paul Cercueil <>,
        Philipp Zabel <>,
        "Rafael J. Wysocki" <>,
        Rob Clark <>,
        Russell King <>,
        Russell King <>,
        Russell King <>,
        Sandy Huang <>,
        Saravana Kannan <>,
        Sebastian Reichel <>,
        Seung-Woo Kim <>,
        Takashi Iwai <>,
        Tian Tao <>,
        Tomas Winkler <>,
        Tomi Valkeinen <>,
        Will Deacon <>,
        Xinliang Liu <>,
        Xinwei Kong <>,
        Yong Wu <>
Subject: Re: [PATCH v2 00/34] component: Make into an aggregate bus

Hi Stephen,

On 06.10.2021 21:37, Stephen Boyd wrote:
> This series is from discussion we had on reordering the device lists for
> drm shutdown paths[1]. I've introduced an 'aggregate' bus that we put
> the aggregate device onto and then we probe the aggregate device once
> all the components are probed and call component_add(). The probe/remove
> hooks are where the bind/unbind calls go, and then a shutdown hook is
> added that can be used to shutdown the drm display pipeline at the right
> time.
> This works for me on my sc7180 board. I no longer get a warning from i2c
> at shutdown that we're trying to make an i2c transaction after the i2c
> bus has been shutdown. There's more work to do on the msm drm driver to
> extract component device resources like clks, regulators, etc. out of
> the component bind function into the driver probe but I wanted to move
> everything over now in other component drivers before tackling that
> problem.

As I understand you have DSI host with i2c-controlled DSI bridge. And 
there is an issue that bridge is shutdown before msmdrm. Your solution 
is to 'adjust' device order on pm list.
I had similar issue and solved it locally by adding notification from 
DSI bridge to DSI host that is has to be removed: mipi_dsi_detach, this 
notification escalates in DSI host to component_del and this allow to 
react properly.

- it is local (only involves DSI host and DSI device),
- it does not depend on PM internals,
- it can be used in other scenarios as well - unbinding DSI device driver

- It is DSI specific (but this is your case), I have advertised some 
time ago more general approach [1][2].



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