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 3B81EC02194 for ; Wed, 5 Feb 2025 13:44:32 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 052EE10E7B0; Wed, 5 Feb 2025 13:44:32 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="i3eQkPnl"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6CF9D10E7B0; Wed, 5 Feb 2025 13:44:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1738763071; x=1770299071; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=pZuQOs0ezi3gK/5h3906HBUA9ZpL+1+rDBjo3QVvfHg=; b=i3eQkPnlvZ07EXYpnR5TztDvple49mzfOcV4X3yY/NZ8H+z4+X+HT+db 514y41QVsPEUmhfE27aGXCfn44siHP3gEBcHiolvBoyS8Xy4n5Km+qbos Ive/lYv1if44DIyhulkvxxDGr/XuwG/2wrag8E0xlZW0caPYE85CkAx76 nUJrtcMcQu3EA56wYk5pHzkf+41cuL2pJs1JmcTFw0VMNA+MEXpLsbCcL nCn8O+NxfF45Llz1D8lEwWhQB0Re2hZ3xcHMQsxQMicPfkmeXQn44Ayho HyyQYPBxG9UNGkjAH6GUn0vz3qEIdxQyP4w9a1qTICLMdA7aM1pk1qBp3 Q==; X-CSE-ConnectionGUID: tT+BCx7JTWCzGsG/opqB1g== X-CSE-MsgGUID: sMfpCWufTf+ZhafuRuN4Cw== X-IronPort-AV: E=McAfee;i="6700,10204,11336"; a="38533866" X-IronPort-AV: E=Sophos;i="6.13,261,1732608000"; d="scan'208";a="38533866" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Feb 2025 05:44:31 -0800 X-CSE-ConnectionGUID: iTxNbSnQTTehHI4EK+XCQA== X-CSE-MsgGUID: txM82kzESNqKRWgH+f7hYw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="111347119" Received: from jkrzyszt-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.246.217]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Feb 2025 05:42:02 -0800 From: Jani Nikula To: imre.deak@intel.com Cc: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Subject: Re: [PATCH] drm/i915/mst: fix INT_MAX to .4 fixed point conversion mistake In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20250204153717.2996923-1-jani.nikula@intel.com> Date: Wed, 05 Feb 2025 15:41:59 +0200 Message-ID: <8734gs4ifs.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain 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, 04 Feb 2025, Imre Deak wrote: > On Tue, Feb 04, 2025 at 05:37:17PM +0200, Jani Nikula wrote: >> intel_dp_mtp_tu_compute_config() conversion to use .4 fixed point didn't >> take into account that intel_dp_mst_max_dpt_bpp() may return INT_MAX >> when the transport limitation is not relevant. Converting INT_MAX to .4 >> fixed point results in -1.0, which then gets used as if it were a real >> max BPP value: >> >> i915 0000:00:02.0: [drm:intel_dp_mtp_tu_compute_config [i915]] Limiting bpp to max DPT bpp (24.0000 -> -1.0000) >> i915 0000:00:02.0: [drm:intel_dp_mtp_tu_compute_config [i915]] Looking for slots in range min bpp 18.0000 max bpp -1.0000 >> >> Just return 0 for "no max DPT BPP", and handle it explicitly. >> >> Fixes: 67782bf6e8a6 ("drm/i915/mst: Convert intel_dp_mtp_tu_compute_config() to .4 format") >> Cc: Imre Deak >> Signed-off-by: Jani Nikula > > Reviewed-by: Imre Deak Pushed to din, thanks for the review! > >> --- >> drivers/gpu/drm/i915/display/intel_dp_mst.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c >> index b729e27cdde2..95abc6ea85eb 100644 >> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c >> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c >> @@ -111,7 +111,7 @@ static int intel_dp_mst_max_dpt_bpp(const struct intel_crtc_state *crtc_state, >> &crtc_state->hw.adjusted_mode; >> >> if (!intel_dp_is_uhbr(crtc_state) || DISPLAY_VER(display) >= 20 || !dsc) >> - return INT_MAX; >> + return 0; >> >> /* >> * DSC->DPT interface width: >> @@ -248,7 +248,7 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp, >> } >> >> max_dpt_bpp_x16 = fxp_q4_from_int(intel_dp_mst_max_dpt_bpp(crtc_state, dsc)); >> - if (max_bpp_x16 > max_dpt_bpp_x16) { >> + if (max_dpt_bpp_x16 && max_bpp_x16 > max_dpt_bpp_x16) { >> drm_dbg_kms(display->drm, "Limiting bpp to max DPT bpp (" FXP_Q4_FMT " -> " FXP_Q4_FMT ")\n", >> FXP_Q4_ARGS(max_bpp_x16), FXP_Q4_ARGS(max_dpt_bpp_x16)); >> max_bpp_x16 = max_dpt_bpp_x16; >> -- >> 2.39.5 >> -- Jani Nikula, Intel