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 C4816F364B6 for ; Thu, 9 Apr 2026 21:11:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 32C8310E06F; Thu, 9 Apr 2026 21:11:39 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="lf1iogsl"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0CF5510E06F for ; Thu, 9 Apr 2026 21:11:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1775769098; x=1807305098; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=+UTAFOZdEierpJ/Jy1ACLQaKBicBNb3LQsO/40pLYSU=; b=lf1iogsligu+ZgbpFc9N9CN2Z8xkrCTX9NR9ZLHiGh312jumjTgTnFqF SXSDiwrfb08waJaD+fnc42fXZ0INxHfC4MNIG3jY3hICXrMbNXBSq3r1G e8CsT0LtI6TuCo+EBrIhFPWp0IedLYy3Bh24W8k2TzeESN8dzcrtMAt5n 9OZWOM7QveKXuwEr2foNYjd1V2LBA+hLbGXvgooU3ExXYSibAE6tjQeTy sHr4Nvc8jH1D4ECkjyvwes1B+NbouvhdsjMWAcau4lQddt3YPp+jNdPAV pX/FvHDjfgz8TsdHcpRH6hP5It9SA37CtWba5/hJKtMgp/ObD6skZHTC6 Q==; X-CSE-ConnectionGUID: DsQewMvySMa2A6eiuzCi2g== X-CSE-MsgGUID: Y73PJj0NTIuXVJCaeQsULQ== X-IronPort-AV: E=McAfee;i="6800,10657,11754"; a="76675401" X-IronPort-AV: E=Sophos;i="6.23,170,1770624000"; d="scan'208";a="76675401" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Apr 2026 14:11:38 -0700 X-CSE-ConnectionGUID: JOuHzg7GRhOcrFujy+YCnw== X-CSE-MsgGUID: bmH92uM4Tq2ENroRpmLuxw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,170,1770624000"; d="scan'208";a="229179894" Received: from hrotuna-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.245.216]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Apr 2026 14:11:36 -0700 Date: Fri, 10 Apr 2026 00:11:33 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jonathan Cavitt Cc: intel-gfx@lists.freedesktop.org, saurabhg.gupta@intel.com, alex.zuo@intel.com Subject: Re: [PATCH] drm/i915/display: Check some INVALID_TRANSCODER cases Message-ID: References: <20260409210001.64901-2-jonathan.cavitt@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260409210001.64901-2-jonathan.cavitt@intel.com> X-Patchwork-Hint: comment Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland 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 Thu, Apr 09, 2026 at 09:00:02PM +0000, Jonathan Cavitt wrote: > There are some cases in intel_ddi.c, such as in intel_ddi_is_audio_enabled > and intel_ddi_compute_config_late, where we attempt to perform a BIT > shift using a passed transcoder enum value. This value may be -1, > INVALID_TRANSCODER, which can result in undefined behavior if this > occurs. > > In the former case, we can simply return false if this is the transcoder > passed (as audio is not enabled on an invalid transcoder). > > In the latter case, the likely expected behavior is to set the > crtc_state->sync_mode_slaves_mask to zero, so just do that directly and > avoid a risky bit shift. > > The likelihood of either case occurring during normal execution is > unknown and possibly very low. Regardless, this covers a static analyis > issue. > > Signed-off-by: Jonathan Cavitt > --- > drivers/gpu/drm/i915/display/intel_ddi.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c > index 178074316a2c..7abeb60779e5 100644 > --- a/drivers/gpu/drm/i915/display/intel_ddi.c > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c > @@ -3875,7 +3875,8 @@ static void intel_ddi_set_idle_link_train(struct intel_dp *intel_dp, > static bool intel_ddi_is_audio_enabled(struct intel_display *display, > enum transcoder cpu_transcoder) > { > - if (cpu_transcoder == TRANSCODER_EDP) > + if (cpu_transcoder == TRANSCODER_EDP || > + cpu_transcoder == INVALID_TRANSCODER) > return false; > > if (!intel_display_power_is_enabled(display, POWER_DOMAIN_AUDIO_MMIO)) > @@ -4637,8 +4638,13 @@ static int intel_ddi_compute_config_late(struct intel_encoder *encoder, > > if (crtc_state->master_transcoder == crtc_state->cpu_transcoder) { > crtc_state->master_transcoder = INVALID_TRANSCODER; > - crtc_state->sync_mode_slaves_mask = > - port_sync_transcoders & ~BIT(crtc_state->cpu_transcoder); > + if (crtc_state->cpu_transcoder == INVALID_TRANSCODER || > + !port_sync_transcoders) > + crtc_state->sync_mode_slaves_mask = 0; > + else > + > + crtc_state->sync_mode_slaves_mask = > + port_sync_transcoders & ~BIT(crtc_state->cpu_transcoder); Making the code convoluted just to satisfy some dumb static analysis tool is not great. If we really need to care about this crap then I think it'd be better to introduce some kind of intel_transcoder_mask() function that explicitly deals with INVALID_TRANSCODER. > } > > return 0; > -- > 2.43.0 -- Ville Syrjälä Intel