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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_GIT 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 8A0FBC4360F for ; Wed, 27 Mar 2019 18:26:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50C6220449 for ; Wed, 27 Mar 2019 18:26:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711215; bh=ifyBJmvU5x3CJzsNRKEbjYFDX0xTqN86y560fUi/TJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tG5sl8mGlfwcLcKtqtGWxyhG2Yb0Ft7TWkJ5shV1grl7FVGyWbA//hOjkbaruxonw ufWLb5i6uvjwIZPoFkV1sAiMFoFiXOsYROG6ZKb1Yx1QAsKa2i/1T3uNqEybV1wf+y SrPfzhA7SacrtUwoOssyKagzdEYVlxH+n0jV2suo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391781AbfC0S0x (ORCPT ); Wed, 27 Mar 2019 14:26:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:46412 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391721AbfC0S0f (ORCPT ); Wed, 27 Mar 2019 14:26:35 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 37DDC206BA; Wed, 27 Mar 2019 18:26:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553711194; bh=ifyBJmvU5x3CJzsNRKEbjYFDX0xTqN86y560fUi/TJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=THqHK20KNxvFuLZxe450QrpyTBMFjOo1Wyh5OnvpwmwTexSF1ba5BYEZBk1vZYbUg VfZUCPR49WPEfVrzW6dRIB1LrsBGCA01Uz3yugKWdwAqNcVAJKHWZ+xCrSPBaUOIZN B9MIgBTLCLRaGrvEs3RNUcVMxQ9b6Np/p+7Fmk7s= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Brian Vincent , Sasha Levin , dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 3.18 41/41] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers Date: Wed, 27 Mar 2019 14:25:18 -0400 Message-Id: <20190327182518.19394-41-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190327182518.19394-1-sashal@kernel.org> References: <20190327182518.19394-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ville Syrjälä [ 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 References: https://bugs.freedesktop.org/show_bug.cgi?id=108081 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 7113c95f5ad0..e4c8c594ea15 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2816,6 +2816,7 @@ 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