Re: [PATCH] iio: ti_am335x_adc: Use same step id at FIFOs both ends

["Zubair Lutfullah :" <zubair.lutfullah@gmail.com>]

On Sat, Jun 21, 2014 at 10:51:35AM +0100, Jonathan Cameron wrote:
> On 11/06/14 22:18, Jan Kardell wrote:
> >Since AI lines could be selected at will (linux-3.11) the sending
> >and receiving ends of the FIFO does not agree about what step is used
> >for a line. It only works if the last lines are used, like 5,6,7,
> >and fails if ie 2,4,6 is selected in DT.
> >
> >Signed-off-by: Jan Kardell <jan.kardell@telliq.com>
> I'd like an ack / review from someone more familiar with this part than I
> am. I have cc'd a few people who might offer a view.

Been a while since I've seen this driver.
I'll try a bit..

> 
> Thanks,
> 
> Jonathan (IIO maintainer)
> >---
> >  drivers/iio/adc/ti_am335x_adc.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> >index a4db302..d5dc4c6 100644
> >--- a/drivers/iio/adc/ti_am335x_adc.c
> >+++ b/drivers/iio/adc/ti_am335x_adc.c
> >@@ -374,7 +374,7 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
> >  			return -EAGAIN;
> >  		}
> >  	}
> >-	map_val = chan->channel + TOTAL_CHANNELS;
> >+	map_val = adc_dev->channel_step[chan->scan_index];

Looking at the code again.
Could you tell me if using map_val = step_en will work?

Checking TRM, the channel ID is written with step id.
And if i am not mistaken, step id is already stored in step_en.
That is the step we enable for sampling.
Would make sense to check fifo for that step no?

something like

@@ -324,7 +324,7 @@
 		int *val, int *val2, long mask)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
-	int i, map_val;
+	int i;
 	unsigned int fifo1count, read, stepid;
 	bool found = false;
 	u32 step_en;
@@ -342,7 +342,6 @@
 		if (time_after(jiffies, timeout))
 			return -EAGAIN;
 		}
-	map_val = chan->channel + TOTAL_CHANNELS;
 
 	/*
 	 * When the sub-system is first enabled,
@@ -361,7 +360,7 @@
 		stepid = read & FIFOREAD_CHNLID_MASK;
 		stepid = stepid >> 0x10;
 
-		if (stepid == map_val) {
+		if (stepid == step_en) {
 			read = read & FIFOREAD_DATA_MASK;
 			found = true;
 			*val = (u16) read;


Cheers
ZubairLK



> >
> >  	/*
> >  	 * We check the complete FIFO. We programmed just one entry but in case
> >
>