From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CBE3F37C910 for ; Fri, 26 Jun 2026 16:51:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782492687; cv=none; b=OWCUwGOu0WzF5K6KuZ4eFnG6YDFFdcArx0L2yPEN4N6/grxou5Nxp4Beuc9BG2FTuqw+ZXwWokXEFf9Z0stNC/zp0OREmpKePD/homdJicPpWAbI+eAGJ/cY50fHer9wCzJToqFPzJ04XYB9jOJWJgv3MUBhd7U4Bjg4vbHS2sk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782492687; c=relaxed/simple; bh=6MXzkFS2E47SUNsfu3fRHzDB0jzVuWRLm15Goqy+6vE=; h=Mime-Version:Content-Type:Date:Message-Id:Cc:To:From:Subject: References:In-Reply-To; b=FXpCsQ+oWVkYedz5GNcZ3LCl8p8dk0ThsqAyvHUu+E8uykcSuPrgjsH7maAYjAlDg5xoH+I3DR2jmCwc3xeeV/3mbn9jzZuU1pWu2ZGmcBiAeooqM4v0ZOmeS5EEFVrcnxDkr7H5+gsoPwMqEKrw8t2ATesz22WIBv3BzE0zkFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=co0ZolZJ; arc=none smtp.client-ip=185.171.202.116 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="co0ZolZJ" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id 0750FC5CD6A; Fri, 26 Jun 2026 16:51:33 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id F1E3460232; Fri, 26 Jun 2026 16:51:23 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 42B2D104C9D9B; Fri, 26 Jun 2026 18:51:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1782492682; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=8iEHH7+jMGAu88nTaddZ+kCu6HVN0Ooq1Pzt5v1N4lk=; b=co0ZolZJ858fCfOk8D33vEBCh0s9JzN/MrFxHMj1DWEl0PeQg+TvCZNcOBIk9uJm8A70aQ NtjIEBNc92ycLE6QVXH5Wx9qnfc0mU+Ln60OMBNf/UKB1cKvJgbLHzXBq8rEfVvugoE0zM L7w/q6YkjZrBjop4aIVdjCttWllHn8T8JWL94GdmmD5mJe+APArqEaM4tkXMUI0RxIwLNu HxDcFfDuc8rYTFZFlIqLDDa7aePw9gBvLYD3z4aBlHHR617Z7ZXOoxSDAw+0ac1YH+Hly+ oHDEv37X29MEiyfdk4N+Jf7eQxI5P1uIuINj2LLK9d0l53+EyGdzHOue48e2CQ== Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 26 Jun 2026 18:51:14 +0200 Message-Id: Cc: "Maarten Lankhorst" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Andrzej Hajda" , "Neil Armstrong" , "Robert Foss" , "Laurent Pinchart" , "Jonas Karlman" , "Jernej Skrabec" , "Inki Dae" , "Jagan Teki" , "Marek Szyprowski" , "Marek Vasut" , "Stefan Agner" , "Frank Li" , "Sascha Hauer" , "Pengutronix Kernel Team" , "Fabio Estevam" , "Hui Pu" , "Ian Ray" , "Thomas Petazzoni" , , , , To: "Maxime Ripard" , "Luca Ceresoli" From: "Luca Ceresoli" Subject: Re: [PATCH 05/37] drm/display: bridge-connector: split code creating the connector to a subfunction X-Mailer: aerc 0.21.0 References: <20260519-drm-bridge-hotplug-v1-0-45e2bdb3dfb4@bootlin.com> <20260519-drm-bridge-hotplug-v1-5-45e2bdb3dfb4@bootlin.com> <20260608-mindful-heavy-frigatebird-be9faf@houat> <20260624-proud-unbiased-pony-ecc3c3@houat> <20260626-polite-hairy-perch-25e1aa@houat> <20260626-classy-nightingale-of-romance-1cacad@houat> In-Reply-To: <20260626-classy-nightingale-of-romance-1cacad@houat> X-Last-TLS-Session-Version: TLSv1.3 On Fri Jun 26, 2026 at 4:38 PM CEST, Maxime Ripard wrote: > On Fri, Jun 26, 2026 at 04:16:39PM +0200, Luca Ceresoli wrote: >> Hi Maxime, >> >> On Fri Jun 26, 2026 at 12:09 PM CEST, Maxime Ripard wrote: >> > On Wed, Jun 24, 2026 at 05:47:10PM +0200, Luca Ceresoli wrote: >> >> On Wed Jun 24, 2026 at 1:41 PM CEST, Maxime Ripard wrote: >> >> > Hi,x >> >> > >> >> > On Fri, Jun 12, 2026 at 02:56:24PM +0200, Luca Ceresoli wrote: >> >> >> On Mon Jun 8, 2026 at 1:40 PM CEST, Maxime Ripard wrote: >> >> >> > On Tue, May 19, 2026 at 12:37:22PM +0200, Luca Ceresoli wrote: >> >> >> >> In preparation to introduce bridge hotplug, split out from >> >> >> >> drm_bridge_connector_init() the code adding the drm_connector i= nto a >> >> >> >> dedicated function. This will be needed to be able to add (and = re-add) the >> >> >> >> connector from different code paths. >> >> >> > >> >> >> > Same story here, explaining what you need later on that calls fo= r that >> >> >> > change would be nice. >> >> >> >> >> >> Here's a more verbose version: >> >> >> >> >> >> Currently drm_bridge_connector_init() does two things: >> >> >> >> >> >> * allocate and initialize the drm_bridge_connector >> >> >> (which embeds a drm_connector) >> >> >> * initialize and register the embedded drm_connector >> >> >> >> >> >> For bridge hotplug we need to separate these two actions: >> >> >> >> >> >> * the drm_connector needs to be added and removed at any time= based on >> >> >> hotplug events >> >> >> * the drm_bridge_connector is designated to create and remove= the >> >> >> drm_connector, so it must be persistent for the card lifeti= me >> >> >> >> >> >> As the lifetimes of drm_bridge_connector and drm_connector bec= ome >> >> >> different, we need to create them in different moments. >> >> >> >> >> >> In preparation to support that, split out from >> >> >> drm_bridge_connector_init() the code adding the drm_connector = into a >> >> >> dedicated function. No functional changes, just moving code ar= ound for >> >> >> now. A future commit will make the drm_connector be created ba= sed on >> >> >> hotplug events. >> >> >> >> >> >> Looks good? >> >> > >> >> > The message itself, yes, thanks. >> >> > >> >> > However, I have questions now :) >> >> > >> >> > Do we really expect drm_bridge_connector to stick around when a bri= dge >> >> > gets unplugged? If so, how does it cope with having, say, an HDMI >> >> > connector, and then swapping out the hotplugged part for an LVDS on= e? >> >> > Does the HDMI connector sticks around indefinitely? >> >> >> >> In your example, the HDMI drm_connector would be unregistered and put= on >> >> hotunplug. Its allocation will stick around until the last put but th= at's >> >> quite irrelevant. Then, on plugging the LVDS addon, a new LVDS >> >> drm_connector will be created and registered. >> >> >> >> > *Especially* if we're using overlays for this, I'd expect everythin= g >> >> > after the first hotplugged bridge to be destroyed, no? >> >> >> >> As said, it would be unregistered immediately but might be freed late= r on >> >> if still refcounted. >> >> >> >> This is visible in patches 36+15, the path to follow is: >> >> >> >> drm_bridge_connector_handle_event(event =3D DRM_BRIDGE_DETACHED) [pa= tch 36] >> >> -> drm_bridge_connector_dynconn_release() [patc= h 15] >> >> >> >> Does this solve your concern? >> > >> > Not really, I'm talking about drm_bridge_connector. The fact that >> > bridges are destroyed make sense to me. The fact that >> > drm_bridge_connector sticks around doesn't. It's supposed to be a >> > connector for bridges. If you don't have bridges because they got >> > destroyed, and connector, drm_bridge_connector doesn't have a reason t= o >> > exist anymore, unless it's drm_bridge_hotplug in a trench coat :) >> >> It is not a hotplug-bridge in a trench coat, no :) The code is clear abo= ut >> this. >> >> I'd say with this series a "drm_bridge_connector" is just becoming >> something more (perhaps something else too). Somewhat as "a drm_bridge i= s >> either a bridge or something else". :) >> >> >> But let's leave names aside for a moment. If just looking at the current >> code, the drm_bridge_connector is "a handler, owned by the card/encoder = and >> having the same lifetime, which takes care of drm_connector >> creation/destruction at card probe/removal". >> >> What we need now is just the same plug " and on hotplug events" appended= . >> >> So in both cases there needs to be "a handler persitent with the card". >> >> Do we agree so far? > > Ish. If we go for that, then we need to update the name. drm_connector_manager? drm_bridge_connector_manager? > drm_bridge_connector for something that is neither a bridge or a > connector is not great. > > But even then, I'm not even sure why we need to have that "manager" in > the first place. You want to make bridges be aware if they are the last > in the chain or not. Use that property in attach to either create a > drm_bridge_connector instance if you're last, or attach the next bridge > if you aren't. What? o_O Several encoder drivers have been painfully converted to create a drm_bridge_connector. Now if the bridges start doing it themselves we should go back to those encoder drivers and ditch all the drm_bridge_connector from there? I must be missing something. Can you elaborate on this? Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com