From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B8A4CFA751 for ; Fri, 4 Oct 2024 08:45:31 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D470C10E05E; Fri, 4 Oct 2024 08:45:30 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=linutronix.de header.i=@linutronix.de header.b="4hBaOt+w"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="t47JWeMy"; dkim-atps=neutral Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id 38F8D10E05E; Fri, 4 Oct 2024 08:45:29 +0000 (UTC) Date: Fri, 4 Oct 2024 10:45:25 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1728031527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8x34rOCooANx2CPvYC38nvaHeQEbkpE7k94cNn5Q8YA=; b=4hBaOt+wN5hziqFJheIDNnAETxllALoZiIFlj5hXelmaHn7LKTo/NZ6mFTjYO6g1yh0gEU KD0lCD3J1z42qVIvK+peg5ESyyaovEKMi/vI5Pa9IrjCZrURnxnpLj+v+1wUEBduaTGo8R VmBBJH2pgaHyx2jD40X6jg39iYzRo4lGWBw4py94NM6fDbBZM3Ag1RdFW4yKxPxWOvoIVo g/0eo/6cshrpI01zILFEuwIm31306t8Aeiy2fWOEplPmX7CzQRKckGnV4QJXUTwno0oZ/5 nfkUOxmMFPQg6P2Rw4HAPfKCpkIFJffVupbnXzAUwdX3em9PvWFmp6655AdsJg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1728031527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8x34rOCooANx2CPvYC38nvaHeQEbkpE7k94cNn5Q8YA=; b=t47JWeMyo03rrOWFzkvfe/7iBNILhQ41LMAtE7aTsQnG/oJXRMMvE+JlhNI5lCCAviZhbQ GQ/nzeu3BP0TRfDw== From: Sebastian Andrzej Siewior To: Ville =?utf-8?B?U3lyasOkbMOk?= Cc: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Thomas Gleixner , Tvrtko Ursulin Subject: Re: [PATCH v3 0/8] drm/i915: PREEMPT_RT related fixups. Message-ID: <20241004084525.333iWV-t@linutronix.de> References: <20240628130601.1772849-1-bigeasy@linutronix.de> <20241002162543.TKbd-8g0@linutronix.de> <20241004064951.XLw7TFbS@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 2024-10-04 11:31:22 [+0300], Ville Syrj=C3=A4l=C3=A4 wrote: >=20 > So once vblank evasion has declared things to be safe we might have > as short a time as VBLANK_EVASION_TIME_US to write all the registers. > If the CPU gets stolen from us at that point we can no longer guarantee > anything. The magic value has been tuned empirically over the years, > until we've found something that seems to work well enough, without > being too long to negatively affect performance. what happens if this gets delayed? Just flicker or worse? Is this something that affects all i915 based HW or only old ones? As far as I remember, there is a register lock which is only required on older HW. Sebastian