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 32576C433EF for ; Mon, 13 Dec 2021 11:44:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231378AbhLMLoh (ORCPT ); Mon, 13 Dec 2021 06:44:37 -0500 Received: from mga04.intel.com ([192.55.52.120]:50697 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231463AbhLMLoh (ORCPT ); Mon, 13 Dec 2021 06:44:37 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10196"; a="237451255" X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="237451255" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2021 03:44:37 -0800 X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="681606545" Received: from smile.fi.intel.com ([10.237.72.184]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2021 03:44:35 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.95) (envelope-from ) id 1mwjk2-005bHS-Kl; Mon, 13 Dec 2021 13:43:38 +0200 Date: Mon, 13 Dec 2021 13:43:38 +0200 From: Andy Shevchenko To: tamal.saha@intel.com Cc: wsa@kernel.org, jarkko.nikula@linux.intel.com, linux-i2c@vger.kernel.org, bala.senthil@intel.com Subject: Re: [PATCH v1] i2c: designware: Do not complete i2c read without RX_FULL interrupt Message-ID: References: <20211211041643.21543-1-tamal.saha@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211211041643.21543-1-tamal.saha@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Sat, Dec 11, 2021 at 09:46:43AM +0530, tamal.saha@intel.com wrote: > From: Tamal Saha > > Intel Keem Bay platform supports multimaster operations over same i2c > bus using Synopsis i2c designware IP. When multi masters initiate i2c Synopsys DesignWare (and everywhere else in the text and comments). > operation simultaneously in a loop, SCL line is stucked low forever > after few i2c operations. Following interrupt sequences are observed > in: > working case: TX_EMPTY, RX_FULL and STOP_DET > non working case: TX_EMPTY, STOP_DET, RX_FULL. > > DW_apb_i2c stretches the SCL line when the TX FIFO is empty or when > RX FIFO is full. The DW_apb_i2c master will continue to hold the SCL > line LOW until RX FIFO is read. > > Linux kernel i2c designware software does not handle above non working software --> driver ? > sequence. TX_EMPTY, RX_FULL and STOP_DET routine execution are required > in sequence although RX_FULL interrupt is raised after STOP_DET by > hardware. Clear STOP_DET for following conditions the following (and seems the colon is missed at the end of line) > (STOP_DET ,RX_FULL, rx_outstanding) > Write Operation: (1, 0, 0) > Read Operation: > RX_FULL followed by STOP_DET: (0, 1, 1) -> (1, 0, 0) > STOP_DET followed by RX_FULL: (1, 0, 1) -> (1, 1, 0) > RX_FULL and STOP_DET together: (1, 1, 1) > > Signed-off-by: Tamal Saha > --- > drivers/i2c/busses/i2c-designware-master.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c > index 9b08bb5df38d..9177463c2cbb 100644 > --- a/drivers/i2c/busses/i2c-designware-master.c > +++ b/drivers/i2c/busses/i2c-designware-master.c > @@ -701,7 +701,8 @@ static u32 i2c_dw_read_clear_intrbits(struct dw_i2c_dev *dev) > regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy); > if (stat & DW_IC_INTR_ACTIVITY) > regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy); > - if (stat & DW_IC_INTR_STOP_DET) > + if ((stat & DW_IC_INTR_STOP_DET) && > + ((dev->rx_outstanding == 0) || (stat & DW_IC_INTR_RX_FULL))) > regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy); > if (stat & DW_IC_INTR_START_DET) > regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy); > @@ -723,6 +724,7 @@ static int i2c_dw_irq_handler_master(struct dw_i2c_dev *dev) > if (stat & DW_IC_INTR_TX_ABRT) { > dev->cmd_err |= DW_IC_ERR_TX_ABRT; > dev->status = STATUS_IDLE; > + dev->rx_outstanding = 0; > > /* > * Anytime TX_ABRT is set, the contents of the tx/rx > @@ -745,7 +747,8 @@ static int i2c_dw_irq_handler_master(struct dw_i2c_dev *dev) > */ > > tx_aborted: > - if ((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || dev->msg_err) > + if (((stat & (DW_IC_INTR_TX_ABRT | DW_IC_INTR_STOP_DET)) || dev->msg_err) && > + (dev->rx_outstanding == 0)) > complete(&dev->cmd_complete); > else if (unlikely(dev->flags & ACCESS_INTR_MASK)) { > /* Workaround to trigger pending interrupt */ > -- > 2.17.1 > -- With Best Regards, Andy Shevchenko