From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 906B511722 for ; Thu, 31 Aug 2023 13:58:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1693490305; x=1725026305; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=HglTuLoHbYLIfAQzy82eLjJIMlyaJ7UjkVVkzK1ra54=; b=ThEwHzBRRkBz6Xyn/Q2GebXhYINAEPbZFYRSeK+agzqM1Xg2trFbFSTO 25l0k1RwhCbBFEGNy1hF4lBqBi4B/r9mXuttQ/w+qzjY1Mlr6IyHaLz9c CNgHyZ4JPHQGHy6GWE8TsvdfR+m3C4gXX0A68u+AbiUCxWJxWg/Z90F8f oNjmAFB7bzUIb9Yq73zR3QItxPH0C0x0pxyQ79ErxsXGqS/CDIdP81mhL 44P3Ncs9gpcpBppR4cKwYFnJL/wYRRwOu8UpS9zBSpJl7+56sj+i7MtC6 ij0gT/PlMVxdweb0RuoMSWl3JptYvzcNxo2m52fjFmtUOuzR5ilDwuWgL g==; X-IronPort-AV: E=McAfee;i="6600,9927,10818"; a="355450945" X-IronPort-AV: E=Sophos;i="6.02,216,1688454000"; d="scan'208";a="355450945" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2023 06:58:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10818"; a="805002182" X-IronPort-AV: E=Sophos;i="6.02,216,1688454000"; d="scan'208";a="805002182" Received: from smile.fi.intel.com ([10.237.72.54]) by fmsmga008.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2023 06:58:21 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1qbiBe-005P1x-29; Thu, 31 Aug 2023 16:58:18 +0300 Date: Thu, 31 Aug 2023 16:58:18 +0300 From: Andy Shevchenko To: Stephen Boyd Cc: Mika Westerberg , Hans de Goede , Mark Gross , linux-kernel@vger.kernel.org, patches@lists.linux.dev, platform-driver-x86@vger.kernel.org, Kuppuswamy Sathyanarayanan , Prashant Malani Subject: Re: [PATCH 2/3] platform/x86: intel_scu_ipc: Check status upon timeout in ipc_wait_for_interrupt() Message-ID: References: <20230831011405.3246849-1-swboyd@chromium.org> <20230831011405.3246849-3-swboyd@chromium.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230831011405.3246849-3-swboyd@chromium.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo On Wed, Aug 30, 2023 at 06:14:02PM -0700, Stephen Boyd wrote: > It's possible for the completion in ipc_wait_for_interrupt() to timeout, > simply because the interrupt was delayed in being processed. A timeout > in itself is not an error. This driver should check the status register > upon a timeout to ensure that scheduling or interrupt processing delays > don't affect the outcome of the IPC return value. > > CPU0 SCU > ---- --- > ipc_wait_for_interrupt() > wait_for_completion_timeout(&scu->cmd_complete) > [TIMEOUT] status[IPC_BUSY]=0 > > Fix this problem by reading the status bit in all cases, regardless of > the timeout. If the completion times out, we'll assume the problem was > that the IPC_BUSY bit was still set, but if the status bit is cleared in > the meantime we know that we hit some scheduling delay and we should > just check the error bit. Makes sense, thanks for fixing this! Reviewed-by: Andy Shevchenko Also see below. ... > /* Wait till ipc ioc interrupt is received or timeout in 10 HZ */ Not sure if this comment needs to be updated / amended. ... > status = ipc_read_status(scu); > - if (status & IPC_STATUS_ERR) > - return -EIO; > + if (!(status & IPC_STATUS_BUSY)) > + err = (status & IPC_STATUS_ERR) ? -EIO : 0; > > - return 0; > + return err; I would write it as: status = ipc_read_status(scu); if (status & IPC_STATUS_BUSY) return 0; if (status & IPC_STATUS_ERR) return -EIO; return 0; Also would be good, in case you are not doing it yet, to use --patience when formatting your patches. -- With Best Regards, Andy Shevchenko