From patchwork Thu Jul 23 17:02:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Colin King X-Patchwork-Id: 11681315 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 08280618 for ; Thu, 23 Jul 2020 17:02:39 +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 E3EBF20771 for ; Thu, 23 Jul 2020 17:02:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3EBF20771 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=canonical.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 485AE6E1A8; Thu, 23 Jul 2020 17:02:35 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2DFA26E1A8 for ; Thu, 23 Jul 2020 17:02:33 +0000 (UTC) Received: from 1.general.cking.uk.vpn ([10.172.193.212] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jyebz-0007Ya-Q9; Thu, 23 Jul 2020 17:02:27 +0000 From: Colin King To: Bartlomiej Zolnierkiewicz , Daniel Vetter , Jani Nikula , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH] video: fbdev: fix setting of pixclock because a pass-by-value error Date: Thu, 23 Jul 2020 18:02:27 +0100 Message-Id: <20200723170227.996229-1-colin.king@canonical.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Colin Ian King The pixclock is being set locally because it is being passed as a pass-by-value argument rather than pass-by-reference, so the computed pixclock is never being set in var->pixclock. Fix this by passing by reference. [This dates back to 2002, I found the offending commit from the git history git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git ] Addresses-Coverity: ("Unused value") Fixes: 115f4504a64a ("Removed currcon and other console related code. Very little is now left.") Signed-off-by: Colin Ian King --- drivers/video/fbdev/vga16fb.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/video/fbdev/vga16fb.c b/drivers/video/fbdev/vga16fb.c index a20eeb8308ff..52f273af6cae 100644 --- a/drivers/video/fbdev/vga16fb.c +++ b/drivers/video/fbdev/vga16fb.c @@ -243,7 +243,7 @@ static void vga16fb_update_fix(struct fb_info *info) } static void vga16fb_clock_chip(struct vga16fb_par *par, - unsigned int pixclock, + unsigned int *pixclock, const struct fb_info *info, int mul, int div) { @@ -259,14 +259,14 @@ static void vga16fb_clock_chip(struct vga16fb_par *par, { 0 /* bad */, 0x00, 0x00}}; int err; - pixclock = (pixclock * mul) / div; + *pixclock = (*pixclock * mul) / div; best = vgaclocks; - err = pixclock - best->pixclock; + err = *pixclock - best->pixclock; if (err < 0) err = -err; for (ptr = vgaclocks + 1; ptr->pixclock; ptr++) { int tmp; - tmp = pixclock - ptr->pixclock; + tmp = *pixclock - ptr->pixclock; if (tmp < 0) tmp = -tmp; if (tmp < err) { err = tmp; @@ -275,7 +275,7 @@ static void vga16fb_clock_chip(struct vga16fb_par *par, } par->misc |= best->misc; par->clkdiv = best->seq_clock_mode; - pixclock = (best->pixclock * div) / mul; + *pixclock = (best->pixclock * div) / mul; } #define FAIL(X) return -EINVAL @@ -497,10 +497,10 @@ static int vga16fb_check_var(struct fb_var_screeninfo *var, if (mode & MODE_8BPP) /* pixel clock == vga clock / 2 */ - vga16fb_clock_chip(par, var->pixclock, info, 1, 2); + vga16fb_clock_chip(par, &var->pixclock, info, 1, 2); else /* pixel clock == vga clock */ - vga16fb_clock_chip(par, var->pixclock, info, 1, 1); + vga16fb_clock_chip(par, &var->pixclock, info, 1, 1); var->red.offset = var->green.offset = var->blue.offset = var->transp.offset = 0;