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[165.204.72.6]) by smtp.gmail.com with ESMTPSA id c16-20020a5d4150000000b00317a29af4b2sm1250339wrq.68.2023.09.07.23.59.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 07 Sep 2023 23:59:37 -0700 (PDT) Message-ID: Date: Fri, 8 Sep 2023 08:59:35 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 Subject: Re: [Nouveau] [RFC, drm-misc-next v4 0/9] PCI/VGA: Allowing the user to select the primary video adapter at boot time Content-Language: en-US To: suijingfeng , =?UTF-8?Q?Christian_K=c3=b6nig?= , Sui Jingfeng , Thomas Zimmermann , Bjorn Helgaas , Jani Nikula , Daniel Vetter , "Deucher, Alexander" Cc: nouveau@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-pci@vger.kernel.org References: <20230904195724.633404-1-sui.jingfeng@linux.dev> <44ec8549-dc36-287e-4359-abd3ec8d22d6@suse.de> <5afd2efb-f838-f9b7-02a9-2cf4d4fd2382@loongson.cn> <2adfa653-ac35-d560-be52-c92848a1eef5@gmail.com> <10509692-ce04-e225-5a27-abc955554bdc@gmail.com> <127fab21-bc5c-f782-e42b-1092fbb8df34@amd.com> <39736dad-41e3-8b24-ccef-ac3425a6c9f4@loongson.cn> From: =?UTF-8?Q?Christian_K=c3=b6nig?= In-Reply-To: <39736dad-41e3-8b24-ccef-ac3425a6c9f4@loongson.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Am 07.09.23 um 18:33 schrieb suijingfeng: > Hi, > > > On 2023/9/7 17:08, Christian König wrote: > > >> I strongly suggest that you just completely drop this here > > > Drop this is OK, no problem. Then I will go to develop something else. > This version is not intended to merge originally, as it's a RFC. > Also, the core mechanism already finished, it is the first patch in > this series. > Things left are just policy (how to specify one and parse the kernel > CMD line) and nothing interesting left. > It is actually to fulfill my promise at V3 which is to give some > examples as usage cases. > > >> and go into the AST driver and try to fix it. > > Well, someone tell me that this is well defined behavior yesterday, > which imply that it is not a bug. I'm not going to fix a non-bug. Sorry for that, I wasn't realizing what you are actually trying to do. > But if thomas ask me to fix it, then I probably have to try to fix. > But I suggest if things not broken, don't fix it. Otherwise this may > incur more big trouble. For server's single display use case, it is > good enough. Yeah, exactly that's the reason why you shouldn't mess with this. In theory you could try to re-program the necessary north bridge blocks to make integrated graphics work even if you installed a dedicated VGA adapter, but you will most likely be missing something. The only real fix is to tell the BIOS that you want to use the integrated VGA device even if a dedicated one is detected. If you want to learn more about the background AMD has a bunch of documentation around this on their website: https://www.amd.com/en/search/documentation/hub.html The most interesting document for you is probably the BIOS programming manual, but don't ask me what exactly the title of that one. @Alex do you remember what that was called? IIRC Intel had similar documentations public, but I don't know where to find those of hand. Regards, Christian. > > > Thanks. >