From patchwork Tue Nov 24 01:33:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bard Liao X-Patchwork-Id: 11928721 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, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 D60C8C2D0E4 for ; Tue, 24 Nov 2020 13:27:09 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 055012083E for ; Tue, 24 Nov 2020 13:27:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="QdmDvBvm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 055012083E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 3FFD81683; Tue, 24 Nov 2020 14:26:15 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 3FFD81683 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1606224425; bh=4Uj9+ftJ080EADuBIwMAHIr7CcQrCgxgfu2cp0fKJVM=; h=From:To:Subject:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=QdmDvBvmq4Frx9G8US3MvcA6ZlK1ZaQqdRCZ4jsI/3TH8ySU56gHJP98iG8scw4sI dDI+ebYhv/O9m4zO59wo8Pl6YJJBOYMeuNDKvNNXiDq0OrItkUyxMRqLc1TV80G62F kGoy1DDoVYEiC3hboeZGHOapO+3PfaZPqBPi4iEc= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id B0599F80161; Tue, 24 Nov 2020 14:26:14 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 54D3FF80128; Tue, 24 Nov 2020 14:26:13 +0100 (CET) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 19BECF80128 for ; Tue, 24 Nov 2020 14:26:05 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 19BECF80128 IronPort-SDR: M1GgLsilSQvjfwW3GgR0iaQRNCoIpZUCCwHLnpW3sVi9lsNMaReWl/B+BvMDdsSoRz8RFhGolN T13F6gd9E+xQ== X-IronPort-AV: E=McAfee;i="6000,8403,9814"; a="172039535" X-IronPort-AV: E=Sophos;i="5.78,366,1599548400"; d="scan'208";a="172039535" 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 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> Cc: pierre-louis.bossart@linux.intel.com, vinod.koul@linaro.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, ranjani.sridharan@linux.intel.com, hui.wang@canonical.com, srinivas.kandagatla@linaro.org, jank@cadence.com, mengdong.lin@intel.com, sanyog.r.kale@intel.com, rander.wang@linux.intel.com, bard.liao@intel.com X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" 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];