On Mon, Apr 11, 2016 at 05:28:39PM +0200, Jan Glauber wrote: > From: David Daney <[email protected]> > > Use High-Level Controller (HLC) when possible. The HLC can read/write > up to 8 bytes and is completely optional. The most important difference > of the HLC is that it only requires one interrupt for a transfer > (up to 8 bytes) where the low-level read/write requires 2 interrupts > plus one interrupt per transferred byte. Since the interrupts are costly > using the HLC improves the performance. Also, the HLC provides improved error > handling.
Much better description, thanks!
> + while (1) {
> + val = octeon_i2c_ctl_read(i2c);
> + if (!(val & (TWSI_CTL_STA | TWSI_CTL_STP)));
> + break;
> +
> + /* clear IFLG event */
> + if (val & TWSI_CTL_IFLG)
> + octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
> +
> + if (try++ > 100) {
> + pr_err("%s: giving up\n", __func__);
> + break;
> + }
> +
> + /* spin until any start/stop has finished */
> + udelay(10);
> + }
Maybe you can use one of the readx_poll_timeout() functions?
> +/**
> + * octeon_i2c_hlc_wait - wait for an HLC operation to complete
> + * @i2c: The struct octeon_i2c
> + *
> + * Returns 0 on success, otherwise a negative errno.
> + */
> +static int octeon_i2c_hlc_wait(struct octeon_i2c *i2c)
> +{
> + int time_left;
> +
> + octeon_i2c_hlc_int_enable(i2c);
> + time_left = wait_event_interruptible_timeout(i2c->queue,
> + octeon_i2c_hlc_test_ready(i2c),
> + i2c->adap.timeout);
Have you tested signal handling thoroughly? Most driver dropped the
_interruptible after a while. Mostly they found out that the state
machine of the interrupt handler couldn't gracefully deal with it and
nobody really needed the interruptible. Just saying.
> + octeon_i2c_int_disable(i2c);
> + if (!time_left) {
> + octeon_i2c_hlc_int_clear(i2c);
> + dev_dbg(i2c->dev, "%s: timeout\n", __func__);
> + return -ETIMEDOUT;
> + }
> +
> + if (time_left < 0) {
> + dev_dbg(i2c->dev, "%s: wait interrupted\n", __func__);
> + return time_left;
> + }
> + return 0;
> +}
Drop the debug messages?
I can't say much about the HW details, of course. Didn't spot anything
suspicious there.
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