Re: [PATCH v4 1/2] phy: qcom: Add driver for QCOM APQ8064 SATA PHY

[Srinivas Kandagatla]

On 15/07/14 17:56, Bartlomiej Zolnierkiewicz wrote:
> > +
> > >+/* Helper function to do poll and timeout */
> > >+static int read_poll_timeout(void __iomem *addr, u32 mask)
> > >+{
> > >+	unsigned long timeout = jiffies + msecs_to_jiffies(TIMEOUT_MS);
> > >+
> > >+	do {
> > >+		if (readl_relaxed(addr) & mask)
> > >+			return 0;
> > >+
> > >+		 usleep_range(DELAY_INTERVAL_US, DELAY_INTERVAL_US + 50);
> > >+	} while (!time_after(jiffies, timeout));
> > >+
> > >+	return -ETIMEDOUT;
> > >+}
> Thanks for reworking this code, unfortunately it still has a one
> (unlikely but still theoretically possible) problem.  If there is
> i.e. a big IRQ load between first usleep_range() call and first

Very unlikely but as you said it possible in theory :-)

> time_after() check the function will timeout without checking
> the register.  To fix it you needs to add an additonal register
> checking before returning -ETIMEDOUT value or replace time_after()
> condition with a fixed number of retries (100000 to cover 1sec
> timeout).
I will send out a fix on top of my previous patches to fix this.

thanks,
srini
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/