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=-15.2 required=3.0 tests=BAYES_00,DATE_IN_PAST_06_12, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 1311CC2D0E4 for ; Tue, 24 Nov 2020 13:26:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B884320782 for ; Tue, 24 Nov 2020 13:26:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388037AbgKXN0I (ORCPT ); Tue, 24 Nov 2020 08:26:08 -0500 Received: from mga03.intel.com ([134.134.136.65]:19615 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728682AbgKXN0D (ORCPT ); Tue, 24 Nov 2020 08:26:03 -0500 IronPort-SDR: LZ6cVZ8EFJlrJC3o9kbp+VdvkW9iX76+OxrFJviOaWFb21drLuX8ABcMHzMeWd1Go9qcMTg+Oj wfle1JFUkG9Q== X-IronPort-AV: E=McAfee;i="6000,8403,9814"; a="172039534" X-IronPort-AV: E=Sophos;i="5.78,366,1599548400"; d="scan'208";a="172039534" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Nov 2020 05:26:02 -0800 IronPort-SDR: P15K+84n5V1KVJuVxYWzDy/ZvAifjRJWVPqU2AXI91CyqvbGYti6bxqQY52QJYsnKPqbO6x9UW XNL3nl0jeb/g== X-IronPort-AV: E=Sophos;i="5.78,366,1599548400"; d="scan'208";a="546830578" Received: from bard-ubuntu.sh.intel.com ([10.239.13.33]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Nov 2020 05:25:58 -0800 From: Bard Liao To: alsa-devel@alsa-project.org, vkoul@kernel.org Cc: vinod.koul@linaro.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, jank@cadence.com, srinivas.kandagatla@linaro.org, rander.wang@linux.intel.com, ranjani.sridharan@linux.intel.com, hui.wang@canonical.com, pierre-louis.bossart@linux.intel.com, sanyog.r.kale@intel.com, mengdong.lin@intel.com, bard.liao@intel.com Subject: [PATCH 1/5] soundwire: bus: add comments to explain interrupt loop filter Date: Tue, 24 Nov 2020 09:33:14 +0800 Message-Id: <20201124013318.8963-2-yung-chuan.liao@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201124013318.8963-1-yung-chuan.liao@linux.intel.com> References: <20201124013318.8963-1-yung-chuan.liao@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pierre-Louis Bossart The interrupt handling in SoundWire requires software to re-read the interrupt status after clearing an interrupt. In case the interrupt is still outstanding, the code in bus.c will loop a number of times, however that loop is limited to the interrupts detected in the first read. This strategy helps meet SoundWire requirements without remaining forever in an interrupt handler. Add a couple of comments to document this design. Signed-off-by: Pierre-Louis Bossart Reviewed-by: Guennadi Liakhovetski Signed-off-by: Bard Liao --- drivers/soundwire/bus.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index ffe4600fd95b..45131b9f5080 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -1334,6 +1334,7 @@ static int sdw_handle_dp0_interrupt(struct sdw_slave *slave, u8 *slave_status) "SDW_DP0_INT read failed:%d\n", status2); return status2; } + /* filter to limit loop to interrupts identified in the first status read */ status &= status2; count++; @@ -1404,6 +1405,7 @@ static int sdw_handle_port_interrupt(struct sdw_slave *slave, "SDW_DPN_INT read failed:%d\n", status2); return status2; } + /* filter to limit loop to interrupts identified in the first status read */ status &= status2; count++; @@ -1589,7 +1591,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) sdca_cascade = ret & SDW_DP0_SDCA_CASCADE; } - /* Make sure no interrupts are pending */ + /* + * Make sure no interrupts are pending, but filter to limit loop + * to interrupts identified in the first status read + */ buf &= _buf; buf2[0] &= _buf2[0]; buf2[1] &= _buf2[1]; -- 2.17.1