From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@bugzilla.kernel.org Subject: [Bug 82781] Option to disable mclk reclocking with AMD R9 280X (TAHITI) to avoid screen flickering on VGA/CRT Date: Tue, 19 Aug 2014 16:27:32 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by gabe.freedesktop.org (Postfix) with ESMTP id 3FE8C6E317 for ; Tue, 19 Aug 2014 09:27:34 -0700 (PDT) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7755D20166 for ; Tue, 19 Aug 2014 16:27:33 +0000 (UTC) Received: from bugzilla1.web.kernel.org (bugzilla1.web.kernel.org [172.20.200.51]) by mail.kernel.org (Postfix) with ESMTP id C17FB2015A for ; Tue, 19 Aug 2014 16:27:32 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org https://bugzilla.kernel.org/show_bug.cgi?id=82781 --- Comment #6 from Alex Deucher --- Since you seem to be using a custom edid, you can also adjust the modelines to increase (to give the GPU more time to switch the mclk) or decrease (to disable mclk switching) the vblank_time. I suspect the vblank period is not reliable on you monitor and since it's currently set to exactly the switching limit the margin for error is very small. The switch may not have finished completely during the vblank period if the vblank period happens to be shorter in some cases. That's why you see the flickering. Tweaking your modeline to increase the vblank period should avoid that. -- You are receiving this mail because: You are watching the assignee of the bug.