Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932221Ab2EXJRb (ORCPT ); Thu, 24 May 2012 05:17:31 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:36805 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924Ab2EXJR3 convert rfc822-to-8bit (ORCPT ); Thu, 24 May 2012 05:17:29 -0400 MIME-Version: 1.0 In-Reply-To: <1337152826-9850-1-git-send-email-sonic.zhang@analog.com> References: <1337152826-9850-1-git-send-email-sonic.zhang@analog.com> Date: Thu, 24 May 2012 17:17:27 +0800 Message-ID: Subject: Re: [PATCH 1/8] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios. From: Sonic Zhang To: sonic.zhang@analog.com Cc: Ben Dooks , Wolfram Sang , linux-i2c@vger.kernel.org, LKML , uclinux-dist-devel@blackfin.uclinux.org, Michael Hennerich Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2330 Lines: 55 PING On Wed, May 16, 2012 at 3:20 PM, wrote: > From: Michael Hennerich > > For transfer counts > 255 bytes i2c-bfin-twi sets the data > transfer counter DCNT to 0xFF indicating unlimited transfers. > It then uses a flag iface->manual_stop to manually issue the STOP > condition, once the required amount of bytes are received. > > We found that on I2C receive operation issuing the STOP condition > together with a FULL RCV FIFO (2bytes) will cause SDA and SCL be > constantly driven low. > > Temporary workaround until further investigation: > Discard the RCV FIFO before issuing the STOP condition. > > Signed-off-by: Michael Hennerich > Signed-off-by: Sonic Zhang > > git-svn-id: svn://localhost/svn/linux-kernel/trunk@9011 526b6c2d-f592-4532-a319-5dd88ccb003d > --- > ?drivers/i2c/busses/i2c-bfin-twi.c | ? ?4 ++++ > ?1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c > index cdb59e5..e6dd3c9 100644 > --- a/drivers/i2c/busses/i2c-bfin-twi.c > +++ b/drivers/i2c/busses/i2c-bfin-twi.c > @@ -131,6 +131,10 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface, > ? ? ? ? ? ? ? ? ? ? ? ?iface->transPtr++; > ? ? ? ? ? ? ? ? ? ? ? ?iface->readNum--; > ? ? ? ? ? ? ? ?} else if (iface->manual_stop) { > + ? ? ? ? ? ? ? ? ? ? ? /* Avoid possible bus stall - > + ? ? ? ? ? ? ? ? ? ? ? ?* Flush FIFO before issuing the STOP condition > + ? ? ? ? ? ? ? ? ? ? ? ?*/ > + ? ? ? ? ? ? ? ? ? ? ? read_RCV_DATA16(iface); > ? ? ? ? ? ? ? ? ? ? ? ?write_MASTER_CTL(iface, > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?read_MASTER_CTL(iface) | STOP); > ? ? ? ? ? ? ? ?} else if (iface->cur_mode == TWI_I2C_MODE_REPEAT && > -- > 1.7.0.4 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at ?http://vger.kernel.org/majordomo-info.html > Please read the FAQ at ?http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/