Re: [PATCH v2 2/2] omap i2c: add a timeout to the busy waiting

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Mar 25, 2010 at 04:38:09 +0200, Aaro Koskinen wrote:
> Hi,
> 
> Alexander Shishkin wrote:
> > 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 <virtuoso@xxxxxxxxx>
> > Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>
> > CC: linux-i2c@xxxxxxxxxxxxxxx
> > CC: linux-omap@xxxxxxxxxxxxxxx
> > CC: nm@xxxxxx
> > ---
> >  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)) {
> 
> This is called from hard interrupt context, so we cannot use jiffies.

Ahh, stupid me. Then we are left with the iteration counting, I guess.

Regards,
--
Alex

--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux GPIO]     [Linux SPI]     [Linux Hardward Monitoring]     [LM Sensors]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux