From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.88]) (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 00E9E138C for ; Tue, 12 Sep 2023 05:00:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694494851; x=1726030851; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=gQCqTAEYQL/pkOw8sp0WLX0nuh/gNZ5sLDu8CpvEilQ=; b=VEJyisadzm02KtB2/Ov0yqBjRV/jcBdKz6/PGIL8K30ElP9AfU7+mkvJ BOfwHsecqZVsXmP3flJICGlTICHvfHKfphJlISmZH+9feNRYfSjnpeAKj 2TctCXccFueaASbeM4i6mSTuJxaD7oBx+hPC/5Z+5BDJYqDhaE/9WV7Oa m93WQgI9dDAHZ9ngbWEIfU8kNBhoGM+MakfIRMWPc++igCdoFcOCci7lo 0dkbW2TK4CG6PWBojgx+SyoWGuOgg/+yxhZAQ/7lBdnCmIwxt1ywdYz1n 1rEMgSaDGO6RWYy5zgT5oTd89XMxs0CTvhEBbE+8DEKFu/SS1Opnq2K5/ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10830"; a="409230168" X-IronPort-AV: E=Sophos;i="6.02,245,1688454000"; d="scan'208";a="409230168" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2023 22:00:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10830"; a="858637789" X-IronPort-AV: E=Sophos;i="6.02,245,1688454000"; d="scan'208";a="858637789" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga002.fm.intel.com with ESMTP; 11 Sep 2023 22:00:47 -0700 Received: by black.fi.intel.com (Postfix, from userid 1001) id EFC82248; Tue, 12 Sep 2023 08:00:45 +0300 (EEST) Date: Tue, 12 Sep 2023 08:00:45 +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 v3 2/4] platform/x86: intel_scu_ipc: Check status upon timeout in ipc_wait_for_interrupt() Message-ID: <20230912050045.GA1599918@black.fi.intel.com> References: <20230911193937.302552-1-swboyd@chromium.org> <20230911193937.302552-3-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: <20230911193937.302552-3-swboyd@chromium.org> On Mon, Sep 11, 2023 at 12:39:34PM -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_STATUS_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_STATUS_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 > Reviewed-by: Kuppuswamy Sathyanarayanan > Reviewed-by: Andy Shevchenko Reviewed-by: Mika Westerberg