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([2a01:e0a:982:cbb0:6124:6b74:2847:d37b]) by smtp.gmail.com with ESMTPSA id q125-20020a1c4383000000b003a5f783abb8sm8990765wma.30.2022.08.29.06.36.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 29 Aug 2022 06:36:25 -0700 (PDT) Message-ID: Date: Mon, 29 Aug 2022 15:36:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] drm/bridge: sii902x: add support for DRM_BRIDGE_ATTACH_NO_CONNECTOR Content-Language: en-US To: Linus Walleij Cc: Dmitry Osipenko , andrzej.hajda@intel.com, robert.foss@linaro.org, Rob Herring , jernej.skrabec@gmail.com, jonas@kwiboo.se, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Laurent.pinchart@ideasonboard.com, Sudeep Holla References: <20220113144305.1074389-1-narmstrong@baylibre.com> <25976b46-21b4-6e3f-0182-85dd4ca2b654@gmail.com> <13bd6440-9a61-d444-518c-f4e8cba0b825@baylibre.com> <5a1df5ce-a497-760b-8e2c-130a0e659c0b@gmail.com> <3725619d-72c5-5c9d-513b-80bbc727dd07@baylibre.com> From: Neil Armstrong Organization: Baylibre In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/08/2022 14:48, Linus Walleij wrote: > On Wed, Aug 17, 2022 at 3:31 PM Neil Armstrong wrote: >> On 15/08/2022 02:15, Dmitry Osipenko wrote: >>> 08.08.2022 12:51, Neil Armstrong пишет: >>>> On 08/08/2022 11:15, Neil Armstrong wrote: > >>>>>> This patch broke ARM/QEMU vexpress display because of_drm_find_bridge() >>>>>> always fail with -EPROBE_DEFER. Reverting this patch returns display >>>>>> back. Please fix or revert, thanks in advance. >>>>> >>>>> Can you share a QEMU cmdline to reproduce ? >>>> >>>> Actually the vexpress DT has multiple input ports instead of a single >>>> input port at @0 >>>> and an output port at @1 like documented in the bindings: >>>> >>>> vexpress-v2m.dtsi#L303-L307: >>>> ports { >>>> #address-cells = <1>; >>>> #size-cells = <0>; >>>> >>>> /* >>>> * Both the core tile and the motherboard routes their output >>>> * pads to this transmitter. The motherboard system controller >>>> * can select one of them as input using a mux register in >>>> * "arm,vexpress-muxfpga". The Vexpress with the CA9 core tile is >>>> * the only platform with this specific set-up. >>>> */ >>>> port@0 { >>>> reg = <0>; >>>> dvi_bridge_in_ct: endpoint { >>>> remote-endpoint = <&clcd_pads_ct>; >>>> }; >>>> }; >>>> port@1 { >>>> reg = <1>; >>>> dvi_bridge_in_mb: endpoint { >>>> remote-endpoint = <&clcd_pads_mb>; >>>> }; >>>> }; >>>> }; >>>> >>>> bindings: >>>> ports: >>>> $ref: /schemas/graph.yaml#/properties/ports >>>> >>>> properties: >>>> port@0: >>>> $ref: /schemas/graph.yaml#/properties/port >>>> description: Parallel RGB input port >>>> >>>> port@1: >>>> $ref: /schemas/graph.yaml#/properties/port >>>> description: HDMI output port >>>> >>>> port@3: >>>> $ref: /schemas/graph.yaml#/properties/port >>>> description: Sound input port >>>> >>>> The patch is conform to the bindings, the DT was working but is actually >>>> not valid. >>> >>> I haven't looked closely at how to fix this properly, but if we can fix >>> it using of_machine_is_compatible("arm,vexpress") workaround in the >>> driver, then it will be good enough at least as a temporal fix, IMO. >> >> If other maintainers are ok with that, it can be temporary fix until the DT gets fixed. > > That's fine with me, will you send a patch? Who, me ? > > I don't know how you expect the DT to get "fixed" though. > > The hardware looks like this, it's maybe not the most elegant > electronics design but it exists, so... I wrote this DT with two > inputs, see commit f1fe12c8bf332, the code handling this > awkward mux is part of the DRM driver, see > drivers/gpu/drm/pl111/pl111_versatile.c function > pl111_vexpress_clcd_init() for an idea of how it works. The proper fix would be the other way around, adding a mux bridge before the sii902x returning the next bridge or nothing to the right controller. > > Yours, > Linus Walleij Neil