linux-kernel - Re: [PATCH v2 17/26] drm/meson: encoder_*: use devm_of_drm_get

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Message-ID: <CAFBinCBaXRNBHpY2uYy4FxyAOnRA4NxJtHbraG0=j_U6Dzz2=A@mail.gmail.com>
Date: Wed, 17 Dec 2025 01:01:40 +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>, 
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	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
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Subject: Re: [PATCH v2 17/26] drm/meson: encoder_*: use devm_of_drm_get_bridge()
 to put the next bridge

Hi Luca,

On Tue, Dec 16, 2025 at 1:46 PM Luca Ceresoli <luca.ceresoli@...tlin.com> wrote:
[...]
> > What I'm not sure about is how this series interacts with
> > devm_drm_of_get_bridge() which is why I'm asking before cooking a
> > patch.
>
> Apologies for the long delay in getting back to you. You might have noticed
> some discussion about the overall approach, and I waited for it to settle.
That hasn't gone unnoticed!

> About devm_drm_of_get_bridge(), it is a very different function so it does
> not affect this series. The name similarity is confusing indeed, but
> devm_of_drm_get_bridge() has been removed from my approach, so one less
> source of confusion.
I have to confess that I'm still confused. drivers/gpu/drm/drm_bridge.c states:
"Display drivers are responsible for linking encoders with the first bridge
 in the chains. This is done by acquiring the appropriate bridge with
 devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
 encoder with a call to drm_bridge_attach().

 Bridges are responsible for linking themselves with the next bridge in the
 chain, if any. This is done the same way as for encoders, with the call to
 drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation."
Does this mean your series effectively deprecates devm_drm_of_get_bridge()?

> I'm soon sending v3, and I have updated my patch to
> eson_encoder_{cvbs,dsi,hdmi}.c, actually splitting it in 3. I'd be grateful
> if you could reviewd and/ot test them when I send v3. But I don't think
> there is a need for you to send any patches related to this topic.
Regardless of the questions I still have around
devm_drm_of_get_bridge(): I'll give your patches a go in the next
days.


Best regards,
Martin