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=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 23D70C4360F for ; Thu, 4 Apr 2019 09:18:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5A6E2147C for ; Thu, 4 Apr 2019 09:18:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369509; bh=4oVFRwTrhSJYqm90AUDvkrAPd5iMpjYa08WCRWwKIfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iAUj/ADHWRNGZ/YIvMQzrzi9hQnWYATlPRkvZf2eQ4OmJ2KLMKNiKQsB3Tu3r6Q7X JJ7IB7qattHjMxEMF/MzAn3H9b7TbmnSqvd6KNZ86p070uxcymmCCcY+PDjvx3Ybof GT9WTigh/W8cyccTNcaT3KFfS4XqPOYzad9fBmUE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388378AbfDDJS1 (ORCPT ); Thu, 4 Apr 2019 05:18:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:60568 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388363AbfDDJSZ (ORCPT ); Thu, 4 Apr 2019 05:18:25 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 9ABD32054F; Thu, 4 Apr 2019 09:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369505; bh=4oVFRwTrhSJYqm90AUDvkrAPd5iMpjYa08WCRWwKIfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KhZwiTn2Ua5HMoq2OC/lTyQxy/gClbOEP9lpCzQ1ZpfyOeUeHPNfiJvgxRJDREnk4 QnWfuSIzlkK8rznVlb9lKWYZjkNfKyc6Y07AnTd+5v6/GlasuIGv+2yMKHy/I/4tgY v3VWp+QcyBNbhfy0mW5GGT9Smagqk5zJ7o9Cx7ro= 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 5.0 241/246] drm/dp/mst: Configure no_stop_bit correctly for remote i2c xfers Date: Thu, 4 Apr 2019 10:49:01 +0200 Message-Id: <20190404084627.735701105@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084619.236418459@linuxfoundation.org> References: <20190404084619.236418459@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 5.0-stable review patch. If anyone has any objections, please let me know. ------------------ [ 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 529414556962..1a244c53252c 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3286,6 +3286,7 @@ 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