From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2339AC433C1 for ; Sun, 21 Mar 2021 18:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF80A6024A for ; Sun, 21 Mar 2021 18:59:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230159AbhCUS6y convert rfc822-to-8bit (ORCPT ); Sun, 21 Mar 2021 14:58:54 -0400 Received: from gloria.sntech.de ([185.11.138.130]:43132 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230060AbhCUS6W (ORCPT ); Sun, 21 Mar 2021 14:58:22 -0400 Received: from p508fc3a3.dip0.t-ipconnect.de ([80.143.195.163] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lO3HC-0006z5-By; Sun, 21 Mar 2021 19:58:14 +0100 From: Heiko Stuebner To: Sandy Huang , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, Jonathan McDowell Subject: Re: [PATCH] drm/rockchip: Cope with endpoints that haven't been registered yet Date: Sun, 21 Mar 2021 19:58:13 +0100 Message-ID: <3104631.44csPzL39Z@phil> In-Reply-To: <20210316182753.GA25685@earth.li> References: <20210316182753.GA25685@earth.li> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="iso-8859-1" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jonathan, Am Dienstag, 16. März 2021, 19:27:53 CET schrieb Jonathan McDowell: > The Rockchip RGB CRTC output driver attempts to avoid probing Rockchip > subdrivers to see if they're a connected panel or bridge. However part > of its checks assumes that if no OF platform device is found then it > can't be a valid bridge or panel. This causes issues with I2C controlled > bridges that have not yet been registered to the point they can be > found. > > Change this to return EPROBE_DEFER instead of ENODEV and don't ignore > such devices. The subsequent call to drm_of_find_panel_or_bridge() will > return EPROBE_DEFER as well if there's actually a valid device we should > wait for. > > Signed-off-by: Jonathan McDowell > --- > drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 8 ++++++-- > drivers/gpu/drm/rockchip/rockchip_rgb.c | 7 ++++--- > 2 files changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c > index 212bd87c0c4a..b0d63a566501 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c > @@ -270,11 +270,15 @@ int rockchip_drm_endpoint_is_subdriver(struct device_node *ep) > if (!node) > return -ENODEV; > > - /* status disabled will prevent creation of platform-devices */ > + /* > + * status disabled will prevent creation of platform-devices, > + * but equally we can't rely on the driver having been registered > + * yet (e.g. I2C bridges). > + */ > pdev = of_find_device_by_node(node); > of_node_put(node); > if (!pdev) > - return -ENODEV; > + return -EPROBE_DEFER; In general, how does that relate to i2c-bridge-drivers, as of_find_device_by_node supposedly only acts on platform-devices? Also if that points to a disabled bridge (hdmi, etc) that would likely make it probe-defer indefinitly, as that device will never become available? Maybe we could do something like of_device_is_available() which checks the status property of the node. So something like: pdev = of_find_device_by_node(node); if (!pdev) { bool avail = of_device_is_available(node); of_node_put(node); /* if disabled if (!avail) return -ENODEV; else return -EPROBE_DEFER; } of_node_put(node); Though I still do not understand how that should actually pick up on i2c devices at all. Heiko