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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 35888C31E57 for ; Mon, 17 Jun 2019 13:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 155CA20657 for ; Mon, 17 Jun 2019 13:33:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727941AbfFQNd1 (ORCPT ); Mon, 17 Jun 2019 09:33:27 -0400 Received: from foss.arm.com ([217.140.110.172]:50190 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726248AbfFQNd1 (ORCPT ); Mon, 17 Jun 2019 09:33:27 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7A2CC28; Mon, 17 Jun 2019 06:33:26 -0700 (PDT) Received: from e110455-lin.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5AB533F246; Mon, 17 Jun 2019 06:33:26 -0700 (PDT) Received: by e110455-lin.cambridge.arm.com (Postfix, from userid 1000) id 260E9682413; Mon, 17 Jun 2019 14:33:25 +0100 (BST) Date: Mon, 17 Jun 2019 14:33:25 +0100 From: Liviu Dudau To: Arnd Bergmann Cc: "James (Qian) Wang" , Brian Starkey , David Airlie , Daniel Vetter , "Lowry Li (Arm Technology China)" , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/komeda: fix 32-bit komeda_crtc_update_clock_ratio Message-ID: <20190617133325.GZ4173@e110455-lin.cambridge.arm.com> References: <20190617125121.1414507-1-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190617125121.1414507-1-arnd@arndb.de> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 17, 2019 at 02:51:04PM +0200, Arnd Bergmann wrote: > clang points out a bug in the clock calculation on 32-bit, that leads > to the clock_ratio always being zero: > > drivers/gpu/drm/arm/display/komeda/komeda_crtc.c:31:36: error: shift count >= width of type [-Werror,-Wshift-count-overflow] > aclk = komeda_calc_aclk(kcrtc_st) << 32; > > Move the shift into the division to make it apply on a 64-bit > variable. Also use the more expensive div64_u64() instead of div_u64() > to account for pxlclk being a 64-bit integer. > > Fixes: a962091227ed ("drm/komeda: Add engine clock requirement check for the downscaling") > Signed-off-by: Arnd Bergmann Acked-by: Liviu Dudau Thanks for the patch, I will pull it into the komeda tree. Best regards, Liviu > --- > drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > index cafb4457e187..3f222f464eb2 100644 > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > @@ -28,10 +28,9 @@ static void komeda_crtc_update_clock_ratio(struct komeda_crtc_state *kcrtc_st) > } > > pxlclk = kcrtc_st->base.adjusted_mode.clock * 1000; > - aclk = komeda_calc_aclk(kcrtc_st) << 32; > + aclk = komeda_calc_aclk(kcrtc_st); > > - do_div(aclk, pxlclk); > - kcrtc_st->clock_ratio = aclk; > + kcrtc_st->clock_ratio = div64_u64(aclk << 32, pxlclk); > } > > /** > -- > 2.20.0 > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯