linux-kernel - Re: [PATCH v3 3/4] drm/bridge: Add devm_drm_bridge

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Date:   Sat, 21 May 2022 11:17:51 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     dri-devel@...ts.freedesktop.org,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Philip Chen <philipchen@...omium.org>,
        Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
        Robert Foss <robert.foss@...aro.org>,
        freedreno@...ts.freedesktop.org,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        linux-arm-msm@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] drm/bridge: Add devm_drm_bridge_add()

Hi,

On Tue, May 10, 2022 at 12:29:43PM -0700, Douglas Anderson wrote:
> This adds a devm managed version of drm_bridge_add(). Like other
> "devm" function listed in drm_bridge.h, this function takes an
> explicit "dev" to use for the lifetime management. A few notes:
> * In general we have a "struct device" for bridges that makes a good
>   candidate for where the lifetime matches exactly what we want.
> * The "bridge->dev->dev" device appears to be the encoder
>   device. That's not the right device to use for lifetime management.
> 
> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>

If we are to introduce more managed helpers, I think it'd be wiser to
introduce them as DRM-managed, and not device managed.

Otherwise, you'll end up in a weird state when a device has been removed
but the DRM device is still around.

Maxime