From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m49205.qiye.163.com (mail-m49205.qiye.163.com [45.254.49.205]) (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 738483AA19D; Tue, 31 Mar 2026 10:55:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.254.49.205 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774954522; cv=none; b=GsBquYujm9At5C5fPtNOKoI+7SihG4W3ADtA4Tka2iGcGzlHHrPJbBA7n9nad/hOIU2+yZq/dgXLlQzT6gNT/zqwLu8CJ15vjOSYQVmUSEd4moYYUuT+h/mz2EmLDfitrHkYCQV2DBFRMzYyvfTZ30VqD7GoQUlZVEu83HXabWw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774954522; c=relaxed/simple; bh=jLrLlHz3Rk6WpLoF/F1IgbWWwVQdwb43ZXK9bMwjong=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EHMZWIB2eKNqBKwsq1FXVDCxt5gOL5RDsTOmtu40WpgFNhGFTiQ9dA59Tlet1EyDb837V78FFxKJWTnOfF1qRoUuOQUYpx43/RNGXJPxrSrpk8L5kUiijunGOiN3JaZ7KzZdTSQzM47v6jAbeQysN9vqseO1S+ZgRhIkGDFGoRs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rock-chips.com; spf=pass smtp.mailfrom=rock-chips.com; dkim=pass (1024-bit key) header.d=rock-chips.com header.i=@rock-chips.com header.b=Gt+84e7R; arc=none smtp.client-ip=45.254.49.205 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rock-chips.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rock-chips.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=rock-chips.com header.i=@rock-chips.com header.b="Gt+84e7R" Received: from [172.16.12.43] (unknown [58.22.7.114]) by smtp.qiye.163.com (Hmail) with ESMTP id 38f48c703; Tue, 31 Mar 2026 15:25:55 +0800 (GMT+08:00) Message-ID: <4fe357a3-2a4a-45fa-8fa2-6e74cd8fe254@rock-chips.com> Date: Tue, 31 Mar 2026 15:25:55 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 06/10] drm/bridge: dw-hdmi: warn on unsupported attach combination To: Luca Ceresoli , Marek Vasut , Stefan Agner , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Frank Li , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Liu Ying , Rob Herring , Saravana Kannan Cc: "Kory Maincent (TI.com)" , =?UTF-8?Q?Herv=C3=A9_Codina?= , Hui Pu , Ian Ray , Thomas Petazzoni , dri-devel@lists.freedesktop.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Adam Ford , Alexander Stein , Christopher Obbard , Daniel Scally , Emanuele Ghidoli , Fabio Estevam , Francesco Dolcini , Frieder Schrempf , Gilles Talis , =?UTF-8?B?R29yYW4gUmHEkWVub3ZpxIc=?= , Heiko Schocher , Josua Mayer , Kieran Bingham , Marco Felsch , Martyn Welch , Oleksij Rempel , Peng Fan , Richard Hu , Shengjiu Wang , Stefan Eichenberger , Vitor Soares References: <20260330-drm-lcdif-dbanc-v2-0-c7f2af536a24@bootlin.com> <20260330-drm-lcdif-dbanc-v2-6-c7f2af536a24@bootlin.com> Content-Language: en-US From: Damon Ding In-Reply-To: <20260330-drm-lcdif-dbanc-v2-6-c7f2af536a24@bootlin.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-HM-Tid: 0a9d42c8e62f03a3kunm0cf998d0a6b464 X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFDSUNOT01LS0k3V1ktWUFJV1kPCRoVCBIfWUFZQk1LGFZJHkxIS0pLTUhCThhWFRQJFh oXVRMBExYaEhckFA4PWVdZGBILWUFZTkNVSUlVTFVKSk9ZV1kWGg8SFR0UWUFZT0tIVUpLSUJNS0 pVSktLVUtZBg++ DKIM-Signature: a=rsa-sha256; b=Gt+84e7Re463RchY6ClojFR1lQV0h32cgP4QGw1Ho9LrRvZtoPjlyJMhBN4/7GfmeYCNggEf3iYwFoO1Apea/XVf5JTqffa0gdlGMYGMkxznzmddrgI3Bv9G9wW6oWK/zjFuYEIbBfqIGS/whL0A23UKaj05z7141AR8BP0AOSA=; c=relaxed/relaxed; s=default; d=rock-chips.com; v=1; bh=goB0cTHExm4jZajm3TogQBTzo9t4lHbQNOdATI5lgbs=; h=date:mime-version:subject:message-id:from; On 3/31/2026 3:25 AM, Luca Ceresoli wrote: > dw-hdmi can operate in two different modes, depending on the platform data > as set by the driver: > > A. hdmi->plat_data->output_port = 0: > the HDMI output (port@1) in device tree is not used > > B. hdmi->plat_data->output_port = 1: > the HDMI output (port@1) is parsed to find the next bridge > > Only case B is supported when the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is > passed to the attach callback. Emit a warning when this is violated. Also > return -EINVAL which would be returned by drm_bridge_attach() right after > anyway. > > Reviewed-by: Liu Ying > Tested-by: Martyn Welch > Tested-by: Alexander Stein # TQMa8MPxL/MBa8MPxL > Signed-off-by: Luca Ceresoli > --- > Note: Returning when the warning triggers does not change the functional > behaviour of this function. It is not strictly necessary in this patch but > it will have to be done anyway in the following patch. > --- > drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > index 0296e110ce65..ab1a6a8783cd 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c > @@ -2910,6 +2910,10 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge, > { > struct dw_hdmi *hdmi = bridge->driver_private; > > + /* DRM_BRIDGE_ATTACH_NO_CONNECTOR requires a remote-endpoint to the next bridge */ > + if (WARN_ON((flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) && !hdmi->plat_data->output_port)) > + return -EINVAL; > + > if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) > return drm_bridge_attach(encoder, hdmi->bridge.next_bridge, > bridge, flags); > Tested-by: Damon Ding (on rk3399) Best regards, Damon