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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 1F9A6C282CE for ; Wed, 22 May 2019 20:00:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBC9120856 for ; Wed, 22 May 2019 20:00:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558555208; bh=eHjR7WKf4S/nm5NSKt//euvYzwhQVvsxfSeDGz2iyFo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lGgKietKMXD62TwgiC2INX0UU9Dkfpk7/cif4KVrlKEOHUthCG0KzPkajm4++Rrvo ojkpwmBlo6rQKARWupdwpNLjsljP9qnN9vx88C78elP78SqRHPfV604fm9NsMuAdq1 RTwkeYDa3nKR5Q+I/nV6Bj0PxkQO2s2EOPlqqtGo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731689AbfEVUAH (ORCPT ); Wed, 22 May 2019 16:00:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:44194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730776AbfEVTXS (ORCPT ); Wed, 22 May 2019 15:23:18 -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 A6E9B2173C; Wed, 22 May 2019 19:23:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558552998; bh=eHjR7WKf4S/nm5NSKt//euvYzwhQVvsxfSeDGz2iyFo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yCRTK4Ly5K8OYW7AkKYL6sUYE1VCUWDuOZ16X6/oV81uzQuMHGahMnH80VY8BveXd 0sX3XtcBDOELyq664UiAaV3wRFFA/rP2p0sl1+w0UNQPDVhxFcyTknrwPtRbJJNHKp 1ms9tAkp09lKAx4EOE0F1jZG297WNSQ4f2/kqPew= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mariusz Bialonczyk , Jean-Francois Dagenais , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 5.1 068/375] w1: fix the resume command API Date: Wed, 22 May 2019 15:16:08 -0400 Message-Id: <20190522192115.22666-68-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522192115.22666-1-sashal@kernel.org> References: <20190522192115.22666-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review 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: Mariusz Bialonczyk [ Upstream commit 62909da8aca048ecf9fbd7e484e5100608f40a63 ] >>From the DS2408 datasheet [1]: "Resume Command function checks the status of the RC flag and, if it is set, directly transfers control to the control functions, similar to a Skip ROM command. The only way to set the RC flag is through successfully executing the Match ROM, Search ROM, Conditional Search ROM, or Overdrive-Match ROM command" The function currently works perfectly fine in a multidrop bus, but when we have only a single slave connected, then only a Skip ROM is used and Match ROM is not called at all. This is leading to problems e.g. with single one DS2408 connected, as the Resume Command is not working properly and the device is responding with failing results after the Resume Command. This commit is fixing this by using a Skip ROM instead in those cases. The bandwidth / performance advantage is exactly the same. Refs: [1] https://datasheets.maximintegrated.com/en/ds/DS2408.pdf Signed-off-by: Mariusz Bialonczyk Reviewed-by: Jean-Francois Dagenais Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/w1/w1_io.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c index 0364d3329c526..3516ce6718d94 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -432,8 +432,7 @@ int w1_reset_resume_command(struct w1_master *dev) if (w1_reset_bus(dev)) return -1; - /* This will make only the last matched slave perform a skip ROM. */ - w1_write_8(dev, W1_RESUME_CMD); + w1_write_8(dev, dev->slave_count > 1 ? W1_RESUME_CMD : W1_SKIP_ROM); return 0; } EXPORT_SYMBOL_GPL(w1_reset_resume_command); -- 2.20.1