Re: [PATCH] i2c-mxs: fixed PIO NACK error instead of timeout (1000ms)

[Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>]

On Tuesday, September 09, 2014 at 06:19:31 PM, Janusz Uzycki wrote:
> i2cdetect scanned i2c bus very slow if address was not occupied by any
> device.

This still fails to explain how the patch fixes the issue. You see, I don't want 
to abuse you unnecessarily, but the commit message serves mostly for the purpose 
of explaining the issue (which you did) and how the change you implemented fixes 
the problem.

So in this case, you should explain that you can use this NO_SLAVE_ACK bit to 
figure out if the peripheral is present. You should also explain that even 
though the mxs_i2c_pio_wait_xfer_end() is called from multiple places, adding 
this particular check will not impact all those other places.

I hope this makes sense. Thank you for the effort though, I really appreciate 
your contributions!

> Signed-off-by: Janusz Uzycki <j.uzycki-9tnw74Q4ehaHKKo6LODCOg@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-mxs.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
> index 87ee72d..35ae448 100644
> --- a/drivers/i2c/busses/i2c-mxs.c
> +++ b/drivers/i2c/busses/i2c-mxs.c
> @@ -307,6 +307,10 @@ static int mxs_i2c_pio_wait_xfer_end(struct
> mxs_i2c_dev *i2c) unsigned long timeout = jiffies +
> msecs_to_jiffies(1000);
> 
>  	while (readl(i2c->regs + MXS_I2C_CTRL0) & MXS_I2C_CTRL0_RUN) {
> +		if (readl(i2c->regs + MXS_I2C_CTRL1) &
> +				MXS_I2C_CTRL1_NO_SLAVE_ACK_IRQ)
> +			return -ENXIO;
>  		if (time_after(jiffies, timeout))
>  			return -ETIMEDOUT;
>  		cond_resched();

Best regards,
Marek Vasut