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 8E507C2D0CD for ; Wed, 21 May 2025 17:41:07 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 524C610E72C; Wed, 21 May 2025 17:41:01 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="lxnaLqE5"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id C4A4110E6FB; Wed, 21 May 2025 17:40:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1747849259; x=1779385259; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=Uj7LFnF+tCuZM/9eDunV1/frFF7klgy1TIn4Rx8/Mr4=; b=lxnaLqE5cevMMddqzXAUKFnEsTE8gCzkXJiI8A2GSpeXHMkEkbNajZvt DA7riSNYnyRfepmAlPVSqKwE4N09Rx5pL9f5J03zMs5fKLEpqL3eJGxmg U+8SF9fDMunx6lMcf+24AIEtPl6mFD5Kljz136TahaDQ4L5QzFK9FJVUJ V6530RRVQwuJY5rZQ/FEUHmoS0MZDEQhuiganky7tJiQlHNPa/7433m+6 6ArZTs3ZQ1eussRhRapTaM3j1cEapOC7/h6Ie8xF1oEfnCKIw2WpJn5gJ mAfO9DIylYOsEJR8m9bM9+aahfH5quxwoDfzHGYJFhgWztc3219AZf8zq g==; X-CSE-ConnectionGUID: dbwPvjWLTxC5xOmWglbyxg== X-CSE-MsgGUID: 1ybxk/EpQAC2AmZ7mrMvvg== X-IronPort-AV: E=McAfee;i="6700,10204,11440"; a="49982501" X-IronPort-AV: E=Sophos;i="6.15,304,1739865600"; d="scan'208";a="49982501" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 May 2025 10:40:59 -0700 X-CSE-ConnectionGUID: Zxy7IhesTPCZ3zeI52lTmQ== X-CSE-MsgGUID: ykxSX9b1SN6gp7n/l1bzVQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.15,304,1739865600"; d="scan'208";a="145311317" Received: from oandoniu-mobl3.ger.corp.intel.com (HELO stinkbox) ([10.245.244.255]) by orviesa005.jf.intel.com with SMTP; 21 May 2025 10:40:57 -0700 Received: by stinkbox (sSMTP sendmail emulation); Wed, 21 May 2025 20:40:56 +0300 Date: Wed, 21 May 2025 20:40:56 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: "Shankar, Uma" Cc: "intel-gfx@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" Subject: Re: [PATCH v2 07/12] drm/i915/flipq: Provide the nuts and bolts code for flip queue Message-ID: References: <20250516113408.11689-8-ville.syrjala@linux.intel.com> <20250519170857.14201-1-ville.syrjala@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Patchwork-Hint: comment X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Tue, May 20, 2025 at 07:06:42AM +0000, Shankar, Uma wrote: > > +static int intel_flipq_exec_time_us(struct intel_display *display) { > > + /* TODO ask the DSB code what this should be */ > > + int dsb_exec_time = 20; > > I think optimum value would be 100. > From bspec: "For the flip queue use case, the recommended DSB execution time is 100us + one SAGV block time" That's just a random number someone pulled out of a hat. We currently use 20 usec for the arming registers writes, and we don't have any estimate for the non-arming stuff since we don't need it. But for flip queue we need to guesstimate the whole thing, so I suppose I might as well slap in a 80usec for the non-arming part now. Ideally we should calculate this based on how many registers we are writing, but that would require measuring the DSB execution speed and coming up with a reasonable formula for it... -- Ville Syrjälä Intel