From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH 3/8] i2c: i2c-bfin-twi: Break dead waiting loop if i2c device misbehaves. Date: Wed, 16 May 2012 15:20:21 +0800 Message-ID: <1337152826-9850-3-git-send-email-sonic.zhang@analog.com> References: <1337152826-9850-1-git-send-email-sonic.zhang@analog.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1337152826-9850-1-git-send-email-sonic.zhang-OyLXuOCK7orQT0dZR+AlfA@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ben Dooks , Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, LKML , uclinux-dist-devel-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org, Sonic Zhang List-Id: linux-i2c@vger.kernel.org From: Sonic Zhang Some fault i2c device may hold the sda/scl line and cause i2c driver wait in the BUS busy loop. This patch breaks this potential dead loop. Signed-off-by: Sonic Zhang git-svn-id: svn://localhost/svn/linux-kernel/trunk@9291 526b6c2d-f592-4532-a319-5dd88ccb003d --- drivers/i2c/busses/i2c-bfin-twi.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c index 376e331..4abaf59 100644 --- a/drivers/i2c/busses/i2c-bfin-twi.c +++ b/drivers/i2c/busses/i2c-bfin-twi.c @@ -294,6 +294,8 @@ static irqreturn_t bfin_twi_interrupt_entry(int irq, void *dev_id) return IRQ_HANDLED; } +#define BFIN_TWI_BUSY_TIMEOUT 1000 + /* * One i2c master transfer */ @@ -303,12 +305,16 @@ static int bfin_twi_do_master_xfer(struct i2c_adapter *adap, struct bfin_twi_iface *iface = adap->algo_data; struct i2c_msg *pmsg; int rc = 0; + unsigned int busy_timeout = BFIN_TWI_BUSY_TIMEOUT; if (!(read_CONTROL(iface) & TWI_ENA)) return -ENXIO; - while (read_MASTER_STAT(iface) & BUSBUSY) + while (read_MASTER_STAT(iface) & BUSBUSY) { + if (--busy_timeout == 0) + return -EBUSY; yield(); + } iface->pmsg = msgs; iface->msg_num = num; @@ -403,12 +409,16 @@ int bfin_twi_do_smbus_xfer(struct i2c_adapter *adap, u16 addr, { struct bfin_twi_iface *iface = adap->algo_data; int rc = 0; + unsigned int busy_timeout = BFIN_TWI_BUSY_TIMEOUT; if (!(read_CONTROL(iface) & TWI_ENA)) return -ENXIO; - while (read_MASTER_STAT(iface) & BUSBUSY) + while (read_MASTER_STAT(iface) & BUSBUSY) { + if (--busy_timeout == 0) + return -EBUSY; yield(); + } iface->writeNum = 0; iface->readNum = 0; -- 1.7.0.4