From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting Date: Mon, 28 Dec 2009 16:15:33 -0800 Message-ID: <20091229001533.GV3512@atomide.com> References: <1261394999-20857-1-git-send-email-virtuoso@slind.org> <1261394999-20857-2-git-send-email-virtuoso@slind.org> <1261394999-20857-3-git-send-email-virtuoso@slind.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1261394999-20857-3-git-send-email-virtuoso@slind.org> Sender: linux-omap-owner@vger.kernel.org To: Alexander Shishkin Cc: ben-linux@fluff.org, nm@ti.com, linux-omap@vger.kernel.org, linux-i2c@vger.kernel.org List-Id: linux-i2c@vger.kernel.org * Alexander Shishkin [091221 03:30]: > The errata 1.153 workaround is busy waiting on XUDF bit in interrupt > context, which may lead to kernel hangs. The problem can be reproduced > by running the bus with wrong (too high) speed. > > Signed-off-by: Alexander Shishkin > CC: linux-i2c@vger.kernel.org > CC: linux-omap@vger.kernel.org > CC: nm@ti.com Acked-by: Tony Lindgren > --- > drivers/i2c/busses/i2c-omap.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > index 2d146ac..7d56a25 100644 > --- a/drivers/i2c/busses/i2c-omap.c > +++ b/drivers/i2c/busses/i2c-omap.c > @@ -678,6 +678,8 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id) > */ > static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err) > { > + unsigned long timeout = jiffies + msecs_to_jiffies(1); > + > while (!(*stat & OMAP_I2C_STAT_XUDF)) { > if (*stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) { > omap_i2c_ack_stat(dev, *stat & (OMAP_I2C_STAT_XRDY | > @@ -685,6 +687,12 @@ static int errata_omap3_1p153(struct omap_i2c_dev *dev, u16 *stat, int *err) > *err |= OMAP_I2C_STAT_XUDF; > return -ETIMEDOUT; > } > + > + if (time_after(jiffies, timeout)) { > + dev_err(dev->dev, "timeout waiting on XUDF bit\n"); > + return 0; > + } > + > cpu_relax(); > *stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG); > } > -- > 1.6.3.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html