From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751945AbdF1XIw (ORCPT ); Wed, 28 Jun 2017 19:08:52 -0400 Received: from gateway33.websitewelcome.com ([192.185.146.82]:15956 "EHLO gateway33.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744AbdF1XIq (ORCPT ); Wed, 28 Jun 2017 19:08:46 -0400 Date: Wed, 28 Jun 2017 18:08:43 -0500 Message-ID: <20170628180843.Horde.KKnryIaN7wki5B896j1w8Sa@gator4166.hostgator.com> From: "Gustavo A. R. Silva" To: "Deucher, Alexander" Cc: "Koenig, Christian" , David Airlie , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [gpu-drm-radeon] question about potential dead code in vce_v2_0_enable_mgcg() References: <20170628092229.Horde.Hsk18WJyYojTJE5OKzhVd3d@gator4166.hostgator.com> In-Reply-To: User-Agent: Horde Application Framework 5 Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes MIME-Version: 1.0 Content-Disposition: inline X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 108.167.133.22 X-Exim-ID: 1dQM4h-002QD9-Ay X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: gator4166.hostgator.com [108.167.133.22]:54902 X-Source-Auth: garsilva@embeddedor.com X-Email-Count: 1 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alex, Quoting "Deucher, Alexander" : >> -----Original Message----- >> From: Gustavo A. R. Silva [mailto:garsilva@embeddedor.com] >> Sent: Wednesday, June 28, 2017 10:22 AM >> To: Deucher, Alexander; Koenig, Christian; David Airlie >> Cc: amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux- >> kernel@vger.kernel.org >> Subject: [gpu-drm-radeon] question about potential dead code in >> vce_v2_0_enable_mgcg() >> >> >> Hello everybody, >> >> While looking into Coverity ID 1198635 I ran into the following piece >> of code at drivers/gpu/drm/radeon/vce_v2_0.c:107: >> >> 107void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) >> 108{ >> 109 bool sw_cg = false; >> 110 >> 111 if (enable && (rdev->cg_flags & >> RADEON_CG_SUPPORT_VCE_MGCG)) { >> 112 if (sw_cg) >> 113 vce_v2_0_set_sw_cg(rdev, true); >> 114 else >> 115 vce_v2_0_set_dyn_cg(rdev, true); >> 116 } else { >> 117 vce_v2_0_disable_cg(rdev); >> 118 >> 119 if (sw_cg) >> 120 vce_v2_0_set_sw_cg(rdev, false); >> 121 else >> 122 vce_v2_0_set_dyn_cg(rdev, false); >> 123 } >> 124} >> >> The issue here is that local variable sw_cg is never updated again >> after its initialization; which cause some code to be logically dead. >> >> My question here is if such variable is there for testing purposes or >> if it is a sort of an old code leftover that should be removed? >> >> In any case I can send a patch to add a comment or remove the dead code. >> >> I'd really appreciate any comments on this. > > I wanted to leave the code in for debugging if we ran into problems > with dynamic clockgating. > Do you mind if I send a patch to add such comment and make it clear the purpose of that variable? --- a/drivers/gpu/drm/radeon/vce_v2_0.c +++ b/drivers/gpu/drm/radeon/vce_v2_0.c @@ -104,6 +104,10 @@ static void vce_v2_0_disable_cg(struct radeon_device *rdev) WREG32(VCE_CGTT_CLK_OVERRIDE, 7); } +/* + * Local variable sw_cg is used for debugging purposes, in case we + * ran into problems with dynamic clock gating. Don't remove it. + */ void vce_v2_0_enable_mgcg(struct radeon_device *rdev, bool enable) { bool sw_cg = false; Thanks for clarifying! -- Gustavo A. R. Silva