From patchwork Sat Jun 16 13:37:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 10469001 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 2CDBE600F4 for ; Sun, 17 Jun 2018 15:50:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2FC912875F for ; Sun, 17 Jun 2018 15:50:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2481D28768; Sun, 17 Jun 2018 15:50:00 +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=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED 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 D861C2875F for ; Sun, 17 Jun 2018 15:49:59 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1DBC26E337; Sun, 17 Jun 2018 15:49:54 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from pokefinder.org (sauhun.de [88.99.104.3]) by gabe.freedesktop.org (Postfix) with ESMTP id DA4706E2A9 for ; Sat, 16 Jun 2018 13:38:29 +0000 (UTC) Received: from localhost (softbank126012118084.bbtec.net [126.12.118.84]) by pokefinder.org (Postfix) with ESMTPSA id 5214E54006A; Sat, 16 Jun 2018 15:38:28 +0200 (CEST) From: Wolfram Sang To: linux-i2c@vger.kernel.org Subject: [PATCH 2/2] i2c: algos: bit: mention our experience about initial states Date: Sat, 16 Jun 2018 22:37:57 +0900 Message-Id: <20180616133757.5994-3-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180616133757.5994-1-wsa+renesas@sang-engineering.com> References: <20180616133757.5994-1-wsa+renesas@sang-engineering.com> X-Mailman-Approved-At: Sun, 17 Jun 2018 15:49:52 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-renesas-soc@vger.kernel.org, Wolfram Sang , dri-devel@lists.freedesktop.org, Sergey Larin MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP So, if somebody wants to re-implement this in the future, we pinpoint to a problem case. Signed-off-by: Wolfram Sang Acked-by: Alex Deucher --- drivers/i2c/algos/i2c-algo-bit.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 0c0eb16d710f..6ec65adaba49 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -647,6 +647,11 @@ static int __i2c_bit_add_bus(struct i2c_adapter *adap, if (bit_adap->getscl == NULL) adap->quirks = &i2c_bit_quirk_no_clk_stretch; + /* + * We tried forcing SCL/SDA to an initial state here. But that caused a + * regression, sadly. Check Bugzilla #200045 for details. + */ + ret = add_adapter(adap); if (ret < 0) return ret;