From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Frysinger Subject: [PATCH 4/4] i2c-bfin-twi: add a timeout to busbusy polling Date: Wed, 25 May 2011 16:26:38 -0400 Message-ID: <1306355198-18530-4-git-send-email-vapier@gentoo.org> References: <1306355198-18530-1-git-send-email-vapier@gentoo.org> Return-path: In-Reply-To: <1306355198-18530-1-git-send-email-vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Ben Dooks Cc: uclinux-dist-devel-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org, Sonic Zhang List-Id: linux-i2c@vger.kernel.org From: Sonic Zhang Some faulty i2c slave devices might hold the sda/scl line and cause the i2c bus driver to wait indefinitely in the busbusy loop. Add a timeout to the loop so the bus master can recover without locking up everything. Signed-off-by: Sonic Zhang Signed-off-by: Mike Frysinger --- 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 64d4b64..f2628a7 100644 --- a/drivers/i2c/busses/i2c-bfin-twi.c +++ b/drivers/i2c/busses/i2c-bfin-twi.c @@ -288,6 +288,8 @@ 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 */ @@ -297,12 +299,16 @@ 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; @@ -397,12 +403,16 @@ 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; -- 1.7.5.rc3