From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [PATCH] i2c: designware: Don't mask TX_EMPTY if write is in progress Date: Fri, 30 Oct 2015 14:03:53 +0200 Message-ID: <56335CA9.7080105@linux.intel.com> References: <1446190649-1318-1-git-send-email-jszhang@marvell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mga03.intel.com ([134.134.136.65]:24900 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758909AbbJ3MD4 (ORCPT ); Fri, 30 Oct 2015 08:03:56 -0400 In-Reply-To: <1446190649-1318-1-git-send-email-jszhang@marvell.com> Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Jisheng Zhang , andriy.shevchenko@linux.intel.com, mika.westerberg@linux.intel.com, wsa@the-dreams.de Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Hi On 10/30/2015 09:37 AM, Jisheng Zhang wrote: > Currently when i2c_msg index search is completed, TX_EMPTY interrupt > will be masked. But if the size of i2c_msg data is longer than the size > of the tx buffer, we still need TX_EMPTY interrupt, otherwise we will > get "controller timed out" error. > > This patch fixes this issue by only masking TX_EMPTY if i2c_msg index > search is completed and write is not in progress. > > Signed-off-by: Jisheng Zhang > --- > drivers/i2c/busses/i2c-designware-core.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c > index 7441cdc..a2eb212 100644 > --- a/drivers/i2c/busses/i2c-designware-core.c > +++ b/drivers/i2c/busses/i2c-designware-core.c > @@ -542,10 +542,11 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev) > } > > /* > - * If i2c_msg index search is completed, we don't need TX_EMPTY > - * interrupt any more. > + * If i2c_msg index search is completed and writing is not in progress, > + * we don't need TX_EMPTY interrupt any more. > */ > - if (dev->msg_write_idx == dev->msgs_num) > + if (dev->msg_write_idx == dev->msgs_num && > + !(dev->status & STATUS_WRITE_IN_PROGRESS)) > intr_mask &= ~DW_IC_INTR_TX_EMPTY; > This looks a possible scenario here. What I'm wondering how is the transfer ending and what condition in i2c_dw_isr() causes the complete() call? Assuming we break the for loop in i2c_dw_xfer_msg() with buf_len > 0 and dev->msg_write_idx == dev->msgs_num how we get back inside the for loop for writing the remaining bytes and stop command? -- Jarkko