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Fri, 29 Apr 2022 01:06:56 -0700 (PDT) X-Received: by 2002:a05:600c:4ec6:b0:394:1f35:4c69 with SMTP id g6-20020a05600c4ec600b003941f354c69mr1623967wmq.61.1651219616352; Fri, 29 Apr 2022 01:06:56 -0700 (PDT) Received: from [192.168.1.129] ([92.176.231.205]) by smtp.gmail.com with ESMTPSA id z11-20020a7bc14b000000b0039419dfbb39sm2210341wmi.33.2022.04.29.01.06.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 Apr 2022 01:06:54 -0700 (PDT) Message-ID: <97339148-9876-cfc1-8df8-dbb21a9c3c7c@redhat.com> Date: Fri, 29 Apr 2022 10:06:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v3 0/5] Fix some race conditions that exists between fbmem and sysfb Content-Language: en-US To: Thomas Zimmermann , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, Alex Deucher , Borislav Petkov , Changcheng Deng , Hans de Goede , Helge Deller , Johan Hovold , Jonathan Corbet , Miaoqian Lin , Peter Jones , Sam Ravnborg , Tetsuo Handa , Yizhuo Zhai , Zhen Lei , linux-doc@vger.kernel.org, linux-fbdev@vger.kernel.org References: <20220420085303.100654-1-javierm@redhat.com> <535ebbe4-605c-daf5-1afb-f5225e4bb3a8@suse.de> <093d742f-4c87-2ff3-e9fe-153cd734f8e4@suse.de> <220929be-91c4-d19c-b04f-312c5f7e9e40@redhat.com> From: Javier Martinez Canillas In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,RDNS_NONE,SPF_HELO_NONE, T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Daniel, On 4/29/22 09:47, Daniel Vetter wrote: [snip] >> >> Exactly, should be done when the device is registered rather than when >> the driver is registered or a call is made to remove the conflicting FB. >> >> I'll rework this series with only the bits for sysfb_disable() and drop >> the rest. We can go back to the discussion of the remaining parts later >> if that makes sense (I still think that patch 3/5 is a better approach, >> but let's defer that for a different series). > > We need to kill sysfb _before_ the driver loads, otherwise you can have > two drivers fighting over each another. And yes that means you might end > up with black screen if the driver load goes wrong, but the two drivers > fighting over each another can also result in black screens. And the > latter isn't fixable any other way (in general at least) than by making > sure the fw stuff is gone before driver load starts in earnest. Yes, you are correct. I didn't realize all the possible cases when agreed with Thomas about doing this but tried and found that it's not enough. I've a full patch-set now and will post as a RFC so we can discuss more. > -Daniel -- Best regards, Javier Martinez Canillas Linux Engineering Red Hat