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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47A67ECAAA1 for ; Mon, 12 Sep 2022 12:00:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230026AbiILMA3 (ORCPT ); Mon, 12 Sep 2022 08:00:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229989AbiILMAQ (ORCPT ); Mon, 12 Sep 2022 08:00:16 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E3B22FFEE for ; Mon, 12 Sep 2022 05:00:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1662984015; x=1694520015; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=zkOXQ6fic21iBzYMitvf8khwq2yyDU+RwPlIGr7j6/o=; b=XZ66qjPgwf02zEUJu7xVJsocl4+FYFtbcEw/06SaEqnruzU6RoUyLOgI Oq60kxJ9GH87hrbg1IzlIKHiMbXYQESKZgXgPsVLhWgP5JTuCwgB1rWIE z+OMNclFVUZfCa9x/LwdiVf/Xn4fFuLg2YPUsmU6550V63CTWgZG2Jbtf g3zutcFrsJvgX2up8dSSZN6/VteR+r13MKOjs91SbUyrVGFRN96BpCxGu MwM2l5s4furunvDvZrLSM8VerR6PFMoUtvsxkS7KFNClhFDa47vNg/w+P tTn1Imjrf+4FArWmTRcP/XmJEXEDrLKQuDavlLZevfWNJb0zTlP6F3+U5 A==; X-IronPort-AV: E=McAfee;i="6500,9779,10467"; a="296581473" X-IronPort-AV: E=Sophos;i="5.93,310,1654585200"; d="scan'208";a="296581473" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Sep 2022 05:00:14 -0700 X-IronPort-AV: E=Sophos;i="5.93,310,1654585200"; d="scan'208";a="705126574" Received: from vtsymbal-mobl.ger.corp.intel.com (HELO [10.252.32.67]) ([10.252.32.67]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Sep 2022 05:00:11 -0700 Message-ID: <35122b05-4d2f-8c9c-eb5e-c0f96ef585a4@linux.intel.com> Date: Mon, 12 Sep 2022 13:05:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.11.0 Subject: Re: [PATCH v2 4/5] soundwire: cadence: Fix lost ATTACHED interrupts when enumerating Content-Language: en-US To: Richard Fitzgerald , vkoul@kernel.org, yung-chuan.liao@linux.intel.com, sanyog.r.kale@intel.com Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, patches@opensource.cirrus.com References: <20220907085259.3602-1-rf@opensource.cirrus.com> <20220907085259.3602-5-rf@opensource.cirrus.com> From: Pierre-Louis Bossart In-Reply-To: <20220907085259.3602-5-rf@opensource.cirrus.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/7/22 10:52, Richard Fitzgerald wrote: > The correct way to handle interrupts is to clear the bits we > are about to handle _before_ handling them. Thus if the condition > then re-asserts during the handling we won't lose it. > > This patch changes cdns_update_slave_status_work() to do this. > > The previous code cleared the interrupts after handling them. > The problem with this is that when handling enumeration of devices > the ATTACH statuses can be accidentally cleared and so some or all > of the devices never complete their enumeration. > > Thus we can have a situation like this: > - one or more devices are reverting to ID #0 > > - accumulated status bits indicate some devices attached and some > on ID #0. (Remember: status bits are sticky until they are handled) > > - Because of device on #0 sdw_handle_slave_status() programs the > device ID and exits without handling the other status, expecting > to get an ATTACHED from this reprogrammed device. > > - The device immediately starts reporting ATTACHED in PINGs, which > will assert its CDNS_MCP_SLAVE_INTSTAT_ATTACHED bit. > > - cdns_update_slave_status_work() clears INTSTAT0/1. If the initial > status had CDNS_MCP_SLAVE_INTSTAT_ATTACHED bit set it will be > cleared. > > - The ATTACHED change for the device has now been lost. > > - cdns_update_slave_status_work() clears CDNS_MCP_INT_SLAVE_MASK so > if the new ATTACHED state had set it, it will be cleared without > ever having been handled. > > Unless there is some other state change from another device to cause > a new interrupt, the ATTACHED state of the reprogrammed device will > never cause an interrupt so its enumeration will not be completed. > > Signed-off-by: Richard Fitzgerald > --- > drivers/soundwire/cadence_master.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c > index 245191d22ccd..3acd7b89c940 100644 > --- a/drivers/soundwire/cadence_master.c > +++ b/drivers/soundwire/cadence_master.c > @@ -954,9 +954,22 @@ static void cdns_update_slave_status_work(struct work_struct *work) > u32 device0_status; > int retry_count = 0; > > + /* > + * Clear main interrupt first so we don't lose any assertions > + * the happen during this function. > + */ > + cdns_writel(cdns, CDNS_MCP_INTSTAT, CDNS_MCP_INT_SLAVE_MASK); > + > slave0 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT0); > slave1 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT1); > > + /* > + * Clear the bits before handling so we don't lose any > + * bits that re-assert. > + */ > + cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT0, slave0); > + cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT1, slave1); > + > /* combine the two status */ > slave_intstat = ((u64)slave1 << 32) | slave0; > > @@ -964,8 +977,6 @@ static void cdns_update_slave_status_work(struct work_struct *work) > > update_status: > cdns_update_slave_status(cdns, slave_intstat); > - cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT0, slave0); > - cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT1, slave1); this one is hard to review, if you don't clear the status here, then how does the retry work if there is a new event? Put differently, do we need to retry and the 'goto update_status' any more? > > /* > * When there is more than one peripheral per link, it's > @@ -1001,8 +1012,7 @@ static void cdns_update_slave_status_work(struct work_struct *work) > } > } > > - /* clear and unmask Slave interrupt now */ > - cdns_writel(cdns, CDNS_MCP_INTSTAT, CDNS_MCP_INT_SLAVE_MASK); > + /* unmask Slave interrupt now */ > cdns_updatel(cdns, CDNS_MCP_INTMASK, > CDNS_MCP_INT_SLAVE_MASK, CDNS_MCP_INT_SLAVE_MASK); >