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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 165F1C282DD for ; Thu, 9 Jan 2020 17:18:42 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id E72432067D for ; Thu, 9 Jan 2020 17:18:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E72432067D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 91A046E461; Thu, 9 Jan 2020 17:18:41 +0000 (UTC) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id B557E6E461 for ; Thu, 9 Jan 2020 17:18:39 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Jan 2020 09:18:39 -0800 X-IronPort-AV: E=Sophos;i="5.69,414,1571727600"; d="scan'208";a="216369957" Received: from jnikula-mobl3.fi.intel.com (HELO localhost) ([10.237.66.161]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Jan 2020 09:18:36 -0800 From: Jani Nikula To: Stanislav Lisovskiy , intel-gfx@lists.freedesktop.org In-Reply-To: <20200109165816.12513-1-stanislav.lisovskiy@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20200109165816.12513-1-stanislav.lisovskiy@intel.com> Date: Thu, 09 Jan 2020 19:18:33 +0200 Message-ID: <87pnfso8eu.fsf@intel.com> MIME-Version: 1.0 Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: Bump up CDCLK to eliminate underruns on TGL 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, 09 Jan 2020, Stanislav Lisovskiy wrote: > There seems to be some undocumented bandwidth > bottleneck/dependency which scales with CDCLK, > causing FIFO underruns when CDCLK is too low, > even when it's correct from BSpec point of view. > > Currently for TGL platforms we calculate > min_cdclk initially based on pixel_rate divided > by 2, accounting for also plane requirements, > however in some cases the lowest possible CDCLK > doesn't work and causing the underruns. > > Explicitly stating here that this seems to be currently > rather a Hack, than final solution. > > v2: Use clamp operation instead of min(Matt Roper) > > Signed-off-by: Stanislav Lisovskiy > Bugzilla: https://gitlab.freedesktop.org/drm/intel/issues/402 > --- > drivers/gpu/drm/i915/display/intel_cdclk.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c > index 7d1ab1e5b7c3..23ef30175090 100644 > --- a/drivers/gpu/drm/i915/display/intel_cdclk.c > +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c > @@ -2004,6 +2004,20 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state) > /* Account for additional needs from the planes */ > min_cdclk = max(intel_planes_min_cdclk(crtc_state), min_cdclk); > > + /* > + * HACK. Currently for TGL platforms we calculate > + * min_cdclk initially based on pixel_rate divided > + * by 2, accounting for also plane requirements, > + * however in some cases the lowest possible CDCLK > + * doesn't work and causing the underruns. > + * Explicitly stating here that this seems to be currently > + * rather a Hack, than final solution. > + */ > + if (IS_TIGERLAKE(dev_priv)) > + min_cdclk = clamp(min_cdclk, > + (int)crtc_state->pixel_rate, > + (int)dev_priv->max_cdclk_freq); I don't think you can do that even as a hack. By clamping the required minimum to the max cdclk, you lose the check below. Can't do that. BR, Jani. > + > if (min_cdclk > dev_priv->max_cdclk_freq) { > DRM_DEBUG_KMS("required cdclk (%d kHz) exceeds max (%d kHz)\n", > min_cdclk, dev_priv->max_cdclk_freq); -- Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx