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([2600:1700:a0:3dc8:205:1bff:fec0:b9b3]) by smtp.gmail.com with ESMTPSA id a17-20020a4ae931000000b0032933be7230sm7424481ooe.4.2022.04.20.16.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Apr 2022 16:10:25 -0700 (PDT) From: Bjorn Andersson To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Thierry Reding , Paul Kocialkowski , Rob Clark Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] Revert "drm: of: Properly try all possible cases for bridge/panel detection" Date: Wed, 20 Apr 2022 16:12:29 -0700 Message-Id: <20220420231230.58499-1-bjorn.andersson@linaro.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit '80253168dbfd ("drm: of: Lookup if child node has panel or bridge")' introduced the ability to describe a panel under a display controller without having to use a graph to connect the controller to its single child panel (or bridge). The implementation of this would find the first non-graph node and attempt to acquire the related panel or bridge. This prevents cases where any other child node, such as a aux bus for a DisplayPort controller, or an opp-table to find the referenced panel. Commit '67bae5f28c89 ("drm: of: Properly try all possible cases for bridge/panel detection")' attempted to solve this problem by not bypassing the graph reference lookup before attempting to find the panel or bridge. While this does solve the case where a proper graph reference is present, it does not allow the caller to distinguish between a yet-to-be-probed panel or bridge and the absence of a reference to a panel. One such case is a DisplayPort controller that on some boards have an explicitly described reference to a panel, but on others have a discoverable DisplayPort display attached (which doesn't need to be expressed in DeviceTree). This reverts commit '67bae5f28c89 ("drm: of: Properly try all possible cases for bridge/panel detection")', as a step towards reverting commit '80253168dbfd ("drm: of: Lookup if child node has panel or bridge")'. Signed-off-by: Bjorn Andersson --- drivers/gpu/drm/drm_of.c | 99 ++++++++++++++++++++-------------------- 1 file changed, 49 insertions(+), 50 deletions(-) diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c index f4df344509a8..026e4e29a0f3 100644 --- a/drivers/gpu/drm/drm_of.c +++ b/drivers/gpu/drm/drm_of.c @@ -214,29 +214,6 @@ int drm_of_encoder_active_endpoint(struct device_node *node, } EXPORT_SYMBOL_GPL(drm_of_encoder_active_endpoint); -static int find_panel_or_bridge(struct device_node *node, - struct drm_panel **panel, - struct drm_bridge **bridge) -{ - if (panel) { - *panel = of_drm_find_panel(node); - if (!IS_ERR(*panel)) - return 0; - - /* Clear the panel pointer in case of error. */ - *panel = NULL; - } - - /* No panel found yet, check for a bridge next. */ - if (bridge) { - *bridge = of_drm_find_bridge(node); - if (*bridge) - return 0; - } - - return -EPROBE_DEFER; -} - /** * drm_of_find_panel_or_bridge - return connected panel or bridge device * @np: device tree node containing encoder output ports @@ -259,44 +236,66 @@ int drm_of_find_panel_or_bridge(const struct device_node *np, struct drm_panel **panel, struct drm_bridge **bridge) { - struct device_node *node; - int ret; + int ret = -EPROBE_DEFER; + struct device_node *remote; if (!panel && !bridge) return -EINVAL; - if (panel) *panel = NULL; - if (bridge) - *bridge = NULL; - - /* Check for a graph on the device node first. */ - if (of_graph_is_present(np)) { - node = of_graph_get_remote_node(np, port, endpoint); - if (node) { - ret = find_panel_or_bridge(node, panel, bridge); - of_node_put(node); - - if (!ret) - return 0; - } - } - /* Otherwise check for any child node other than port/ports. */ - for_each_available_child_of_node(np, node) { - if (of_node_name_eq(node, "port") || - of_node_name_eq(node, "ports")) + /** + * Devices can also be child nodes when we also control that device + * through the upstream device (ie, MIPI-DCS for a MIPI-DSI device). + * + * Lookup for a child node of the given parent that isn't either port + * or ports. + */ + for_each_available_child_of_node(np, remote) { + if (of_node_name_eq(remote, "port") || + of_node_name_eq(remote, "ports")) continue; - ret = find_panel_or_bridge(node, panel, bridge); - of_node_put(node); + goto of_find_panel_or_bridge; + } + + /* + * of_graph_get_remote_node() produces a noisy error message if port + * node isn't found and the absence of the port is a legit case here, + * so at first we silently check whether graph presents in the + * device-tree node. + */ + if (!of_graph_is_present(np)) + return -ENODEV; + + remote = of_graph_get_remote_node(np, port, endpoint); + +of_find_panel_or_bridge: + if (!remote) + return -ENODEV; + + if (panel) { + *panel = of_drm_find_panel(remote); + if (!IS_ERR(*panel)) + ret = 0; + else + *panel = NULL; + } + + /* No panel found yet, check for a bridge next. */ + if (bridge) { + if (ret) { + *bridge = of_drm_find_bridge(remote); + if (*bridge) + ret = 0; + } else { + *bridge = NULL; + } - /* Stop at the first found occurrence. */ - if (!ret) - return 0; } - return -EPROBE_DEFER; + of_node_put(remote); + return ret; } EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge); -- 2.35.1