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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 1954DC10F11 for ; Wed, 24 Apr 2019 18:05:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF8CF20652 for ; Wed, 24 Apr 2019 18:05:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556129130; bh=1QXLjvJhZpBC1YwpufBIkYL+Ewqfrz9VcBjmg8DunMM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xxSf17ej7/gbW3qv2YwHw8vM9uJJE3QUrgqV2Qaw0GDBK1PdN5HdXw31Tyahy0gc7 oL/SffZRsheO+UFkmumjJoR+ca8m6SzMPincqI2SYn0wwXu2rlMPwWCLa5aq4luNDa xYl4avU0GexBmZqbjEqpK/O3PkBOFAfcL3x5UJA0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388866AbfDXRSi (ORCPT ); Wed, 24 Apr 2019 13:18:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:43632 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388419AbfDXRSe (ORCPT ); Wed, 24 Apr 2019 13:18:34 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F396621908; Wed, 24 Apr 2019 17:18:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556126313; bh=1QXLjvJhZpBC1YwpufBIkYL+Ewqfrz9VcBjmg8DunMM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i015V+Wb0UUkBaz1mfDpkgF3CpjamzcMNiC09S1svEEZx6spotm4STUDyKSmGF0tb Sl+3h/pLkKYYKtWti++AakAYQnABAY/ho4LmzlOqT9jmAKbYvlOIJ9igulcNSTWgzi 3jbrocUMiBgIwwj9zDzCI6P7Oy/fF4nSfWhIUZJo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brian Vincent , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Dhinakaran Pandiyan , Sasha Levin Subject: [PATCH 4.4 068/168] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers Date: Wed, 24 Apr 2019 19:08:32 +0200 Message-Id: <20190424170927.789312806@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170923.452349382@linuxfoundation.org> References: <20190424170923.452349382@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit c978ae9bde582e82a04c63a4071701691dd8b35c ] We aren't supposed to force a stop+start between every i2c msg when performing multi message transfers. This should eg. cause the DDC segment address to be reset back to 0 between writing the segment address and reading the actual EDID extension block. To quote the E-DDC spec: "... this standard requires that the segment pointer be reset to 00h when a NO ACK or a STOP condition is received." Since we're going to touch this might as well consult the I2C_M_STOP flag to determine whether we want to force the stop or not. Cc: Brian Vincent Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20180928180403.22499-1-ville.syrjala@linux.intel.com Reviewed-by: Dhinakaran Pandiyan Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_dp_mst_topology.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 5a1bafb5ecbb..ff12d926eb65 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3019,6 +3019,7 @@ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr; msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len; msg.u.i2c_read.transactions[i].bytes = msgs[i].buf; + msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP); } msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr; msg.u.i2c_read.num_bytes_read = msgs[num - 1].len; -- 2.19.1