From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.20]) (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 8B01B3FF4 for ; Fri, 1 Sep 2023 06:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1693548294; x=1725084294; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Cft0NZX01jZWskmao0IZaX0TQTrymVnXyHFz/2cvU04=; b=BPsTeSuaLJaygSphHK6Byv0R72wFogtMgIH63ouu9gDDPABxeSgOryRo jEdKNhyoLgFovE2lRrIu1zb/MYay2SIogd7I3+MZjm6m4P+dSMgMFxLin aag/2XWE1IM0+5GTiOt1y8L9XIGKXW5pJzqssxIbSb3GYPPF7dcqhUq0q 30gn8o9g+ZxTVbXHx1a8c9OFKEILTIVTynSDRSS2eRargG13iTNwl+ODc 75GTTFgscAnN6GWv3n+KvdLmyOM+1k09PaMVgTabMmcMkEwWcKMqH9f3j e/ccyvOikQqlKV5kOG5XVknRL1tFIqzZV6gWg2l5N/2Qs7XqdzYSriaYD w==; X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="366372093" X-IronPort-AV: E=Sophos;i="6.02,218,1688454000"; d="scan'208";a="366372093" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2023 23:04:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10819"; a="805310003" X-IronPort-AV: E=Sophos;i="6.02,218,1688454000"; d="scan'208";a="805310003" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga008.fm.intel.com with ESMTP; 31 Aug 2023 23:04:44 -0700 Received: by black.fi.intel.com (Postfix, from userid 1001) id 7DC2FDE; Fri, 1 Sep 2023 09:04:43 +0300 (EEST) Date: Fri, 1 Sep 2023 09:04:43 +0300 From: Mika Westerberg To: Stephen Boyd Cc: Hans de Goede , Mark Gross , linux-kernel@vger.kernel.org, patches@lists.linux.dev, platform-driver-x86@vger.kernel.org, Andy Shevchenko , 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: <20230901060443.GU3465@black.fi.intel.com> 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=utf-8 Content-Disposition: inline In-Reply-To: <20230831011405.3246849-3-swboyd@chromium.org> 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. > > Cc: Prashant Malani > Cc: Kuppuswamy Sathyanarayanan Reviewed-by: Mika Westerberg