Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753507Ab2FMIaR (ORCPT ); Wed, 13 Jun 2012 04:30:17 -0400 Received: from [216.32.180.12] ([216.32.180.12]:38177 "EHLO va3outboundpool.messaging.microsoft.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752137Ab2FMI2F (ORCPT ); Wed, 13 Jun 2012 04:28:05 -0400 X-Forefront-Antispam-Report: CIP:137.71.25.55;KIP:(null);UIP:(null);IPV:NLI;H:nwd2mta1.analog.com;RD:nwd2mail10.analog.com;EFVD:NLI X-SpamScore: 1 X-BigFish: VS1(zzzz1202hzz8275bhz2ei87h2a8h668h839hd24he5bhe96h) X-FB-DOMAIN-IP-MATCH: fail From: Sonic Zhang To: Wolfram Sang , Ben Dooks CC: , LKML , , Michael Hennerich , Sonic Zhang Subject: [PATCH 1/8 v2] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios. Date: Wed, 13 Jun 2012 16:22:40 +0800 Message-ID: <1339575767-22985-1-git-send-email-sonic.adi@gmail.com> X-Mailer: git-send-email 1.7.0.4 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 44 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 --- 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..33031f0 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) { + /* Temporary workaround to 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/