linux-kernel - Re: [PATCH v2 2/6] drm/meson/dw-hdmi: convert to of_drm_find_and_get

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Message-ID: <CAFBinCBWUXNwEDCJNEmdCtOcGO9eVFfZFC9p9fpdRTesZ7xBSQ@mail.gmail.com>
Date: Mon, 12 Jan 2026 23:21:56 +0100
From: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Robert Foss <rfoss@...nel.org>, Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Kevin Hilman <khilman@...libre.com>, Jerome Brunet <jbrunet@...libre.com>, 
	Philipp Zabel <p.zabel@...gutronix.de>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
	Matthias Brugger <matthias.bgg@...il.com>, 
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	Seung-Woo Kim <sw0312.kim@...sung.com>, Kyungmin Park <kyungmin.park@...sung.com>, 
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	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, 
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	Geert Uytterhoeven <geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, 
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	linux-kernel@...r.kernel.org, linux-amlogic@...ts.infradead.org, 
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	linux-mediatek@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH v2 2/6] drm/meson/dw-hdmi: convert to of_drm_find_and_get_bridge()

Hi Luca,

On Fri, Jan 9, 2026 at 11:03 AM Luca Ceresoli <luca.ceresoli@...tlin.com> wrote:
>
> of_drm_find_bridge() is deprecated. Move to its replacement
> of_drm_find_and_get_bridge() which gets a bridge reference, and ensure it
> is put when done.
>
> dw_hdmi->bridge is used only in dw_hdmi_top_thread_irq(), so in order to
> avoid potential use-after-free ensure the irq is freed before putting the
> dw_hdmi->bridge reference.
>
> Acked-by: Maxime Ripard <mripard@...nel.org>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

[...]
> @@ -789,8 +789,12 @@ static void meson_dw_hdmi_unbind(struct device *dev, struct device *master,
>                                    void *data)
>  {
>         struct meson_dw_hdmi *meson_dw_hdmi = dev_get_drvdata(dev);
> +       struct platform_device *pdev = to_platform_device(dev);
> +       int irq = platform_get_irq(pdev, 0);
>
> +       devm_free_irq(dev, irq, meson_dw_hdmi);
I have one question (so I can understand things better):
is there a particular reason why you went with free'ing the IRQ
instead of "just" masking it (so the hardware won't fire anymore of
those IRQs)?


Best regards,
Martin