From nobody Fri Feb 13 21:31:19 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53484CE79AB for ; Wed, 20 Sep 2023 08:27:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233284AbjITI1x (ORCPT ); Wed, 20 Sep 2023 04:27:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbjITI1v (ORCPT ); Wed, 20 Sep 2023 04:27:51 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 697F790 for ; Wed, 20 Sep 2023 01:27:45 -0700 (PDT) Received: from IcarusMOD.eternityproject.eu (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id 4BEBF66003AF; Wed, 20 Sep 2023 09:27:43 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1695198464; bh=DbWGcn6zI7FsJFEu+IPzpjZSXjvXMMCEXJn4aXMt218=; h=From:To:Cc:Subject:Date:From; b=lV+NRHy9R1DzJrhNmu1OqK8DVNExlmtN2Vphj8vkfm0JReVuaE7FnjRtc426NmVX+ SdgJ+NECW6+yMTwVSZSsxZ8L6CR7B9Gl5VpQXzEJVJnLlKZJUTVZQNOhJeIrOLV49j rM8tmDngAf9gWgQRNHQhc+yHVrrzPiJfkTAEEmM/Mq9v2BbVEnnA64THsYqIb2noPd UfFVxgJbixYUadcOwmP1mZZd2ROlztvXAG459sgYKS1Bpf7Aa11vIl9c4Lm0h1d2gn 7IIKSvRXMJ03nsbgTA1xRBZuPtJKfgoLWQhrYw19K6ARmQ4ASh3CwYA5CxVWpOOz9h WA+Nvw+IC9uBA== From: AngeloGioacchino Del Regno To: andrzej.hajda@intel.com Cc: neil.armstrong@linaro.org, rfoss@kernel.org, Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, airlied@gmail.com, daniel@ffwll.ch, ulf.hansson@linaro.org, victor.liu@nxp.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, ehristev@collabora.com, wenst@chromium.org, AngeloGioacchino Del Regno Subject: [PATCH v2] drm/bridge: panel: Fix device link for DRM_BRIDGE_ATTACH_NO_CONNECTOR Date: Wed, 20 Sep 2023 10:27:27 +0200 Message-ID: <20230920082727.57729-1-angelogioacchino.delregno@collabora.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When external bridges are attached with DRM_BRIDGE_ATTACH_NO_CONNECTOR, the panel bridge may also get the same flag, but in the .attach() callback for the panel bridge a device link is added only when this flag is not present; To make things worse, the .detach() callback tries to delete the device link unconditionally and without checking if it was created in the first place, crashing the kernel with a NULL pointer kernel panic upon calling panel_bridge_detach(). Fix that by moving the device_link_add() call before checking if the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is present. Fixes: 199cf07ebd2b ("drm/bridge: panel: Add a device link between drm devi= ce and panel device") Signed-off-by: AngeloGioacchino Del Regno Reviewed-by: Liu Ying --- Changes in v2: - Added device_link_del() for (!bridge->encoder) error condition drivers/gpu/drm/bridge/panel.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index e00d2e94c751..e48823a4f1ed 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -67,14 +67,6 @@ static int panel_bridge_attach(struct drm_bridge *bridge, struct drm_device *drm_dev =3D bridge->dev; int ret; =20 - if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) - return 0; - - if (!bridge->encoder) { - DRM_ERROR("Missing encoder\n"); - return -ENODEV; - } - panel_bridge->link =3D device_link_add(drm_dev->dev, panel->dev, DL_FLAG_STATELESS); if (!panel_bridge->link) { @@ -83,6 +75,15 @@ static int panel_bridge_attach(struct drm_bridge *bridge, return -EINVAL; } =20 + if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) + return 0; + + if (!bridge->encoder) { + DRM_ERROR("Missing encoder\n"); + device_link_del(panel_bridge->link); + return -ENODEV; + } + drm_connector_helper_add(connector, &panel_bridge_connector_helper_funcs); =20 --=20 2.42.0