From patchwork Thu Jan 9 16:58:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Lisovskiy, Stanislav" X-Patchwork-Id: 11326187 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 09DC41395 for ; Thu, 9 Jan 2020 17:03:41 +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 E608420661 for ; Thu, 9 Jan 2020 17:03:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E608420661 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=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 17FFD8999C; Thu, 9 Jan 2020 17:03:39 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7A3248999C for ; Thu, 9 Jan 2020 17:03:37 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Jan 2020 09:00:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,414,1571727600"; d="scan'208";a="396153264" Received: from slisovsk-lenovo-ideapad-720s-13ikb.fi.intel.com ([10.237.72.89]) by orsmga005.jf.intel.com with ESMTP; 09 Jan 2020 09:00:36 -0800 From: Stanislav Lisovskiy To: intel-gfx@lists.freedesktop.org Date: Thu, 9 Jan 2020 18:58:16 +0200 Message-Id: <20200109165816.12513-1-stanislav.lisovskiy@intel.com> X-Mailer: git-send-email 2.24.1.485.gad05a3d8e5 MIME-Version: 1.0 Subject: [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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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 Reviewed-by: Matt Roper --- 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); + 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);