From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH 1/8] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios. Date: Wed, 16 May 2012 15:20:19 +0800 Message-ID: <1337152826-9850-1-git-send-email-sonic.zhang@analog.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Ben Dooks , Wolfram Sang Cc: linux-i2c@vger.kernel.org, LKML , uclinux-dist-devel@blackfin.uclinux.org, Michael Hennerich , Sonic Zhang List-Id: linux-i2c@vger.kernel.org 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