From patchwork Fri Apr 21 10:51:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Carpenter X-Patchwork-Id: 9692447 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D40076037F for ; Fri, 21 Apr 2017 10:52:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C34831FF15 for ; Fri, 21 Apr 2017 10:52:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B821D2860E; Fri, 21 Apr 2017 10:52:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5A14B1FF15 for ; Fri, 21 Apr 2017 10:52:00 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CC1906E42B; Fri, 21 Apr 2017 10:51:59 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from aserp1040.oracle.com (aserp1040.oracle.com [141.146.126.69]) by gabe.freedesktop.org (Postfix) with ESMTPS id 11B396E42B for ; Fri, 21 Apr 2017 10:51:59 +0000 (UTC) Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v3LAptC9004448 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Apr 2017 10:51:55 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id v3LApsKB002792 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Apr 2017 10:51:54 GMT Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id v3LApq21004690; Fri, 21 Apr 2017 10:51:52 GMT Received: from mwanda (/197.254.35.146) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 21 Apr 2017 03:51:51 -0700 Date: Fri, 21 Apr 2017 13:51:43 +0300 From: Dan Carpenter To: CK Hu , shaoming chen Subject: [PATCH v2] drm/mediatek: fix a timeout loop Message-ID: <20170421105143.jbzvbsremnu6ltgp@mwanda> MIME-Version: 1.0 Content-Disposition: inline X-Mailer: git-send-email haha only kidding User-Agent: NeoMutt/20170113 (1.7.2) X-Source-IP: aserv0022.oracle.com [141.146.126.234] Cc: kernel-janitors@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, Matthias Brugger X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP This code causes a static checker warning because it treats "i == 0" as a timeout but, because it's a post-op, the loop actually ends with "i" set to -1. Philipp Zabel points out that it would be cleaner to use readl_poll_timeout() instead. Fixes: 21898816831f ("drm/mediatek: add dsi transfer function") Signed-off-by: Dan Carpenter Reviewed-by: Philipp Zabel --- v2: Use readl_poll_timeout(). Please review this carefully because I've never used readl_poll_timeout() and could easily mess up. diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index 808b995a990f..b5cc6e12334c 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -900,16 +901,12 @@ static int mtk_dsi_host_detach(struct mipi_dsi_host *host, static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi) { - u32 timeout_ms = 500000; /* total 1s ~ 2s timeout */ - - while (timeout_ms--) { - if (!(readl(dsi->regs + DSI_INTSTA) & DSI_BUSY)) - break; - - usleep_range(2, 4); - } + int ret; + u32 val; - if (timeout_ms == 0) { + ret = readl_poll_timeout(dsi->regs + DSI_INTSTA, val, !(val & DSI_BUSY), + 4, 2000000); + if (ret) { DRM_WARN("polling dsi wait not busy timeout!\n"); mtk_dsi_enable(dsi);