Re: [drivers/iio] Question about `iio_gts_build_avail_time_table`

[Matti Vaittinen]

Hi Chenyuan,

On 3/12/24 18:53, Chenyuan Yang wrote:
> Hi Matti,
>
> I have a question about the "The idea of the check which has been
> removed was to assign the value in
> the array in first free spot if it is bigger than the last value".

Can you please avoid top-posting when discussing on the Linux lists. You 
can find more information from:
https://www.kernel.org/doc/html/latest/process/submitting-patches.html

part of which may be crucial in order to get your changes applied if you 
haven't already familiarized yourself with the kernel development processes.


> -               if (times[idx] < new) {
> -                       times[idx++] = new;
> -                       continue;
> -               }
> +               times[idx] = new;
>
> It appears that the comparison should perhaps be made with `idx-1`
> rather than `idx`, given that `idx` represents the current number of
> copied values in times, whereas `idx-1` points to the last value.
> Could I have your thoughts on this?

Yes. I implemented the old code wrong as you pointed out.

You may want to take the GTS Kunit test cases:
https://lore.kernel.org/all/6b839dd533fd93b75c2e6f6a8f2286233d4901fb.1704881096.git.mazziesaccount@xxxxxxxxx/
which, I think, are already merged in IIO testing branch.

You can test the sorting when you change the order of the times in the 
test case:

+static const struct iio_itime_sel_mul gts_test_itimes[] = {
+	GAIN_SCALE_ITIME_US(400 * 1000, TEST_TSEL_400, 8),
+	GAIN_SCALE_ITIME_US(200 * 1000, TEST_TSEL_200, 4),
+	GAIN_SCALE_ITIME_US(100 * 1000, TEST_TSEL_100, 2),
+	GAIN_SCALE_ITIME_US(50 * 1000, TEST_TSEL_50, 1),
+#define TIMEGAIN_MAX 8
+};

for example to

+static const struct iio_itime_sel_mul gts_test_itimes[] = {
+	GAIN_SCALE_ITIME_US(400 * 1000, TEST_TSEL_400, 8),
+	GAIN_SCALE_ITIME_US(50 * 1000, TEST_TSEL_50, 1),
+	GAIN_SCALE_ITIME_US(200 * 1000, TEST_TSEL_200, 4),
+	GAIN_SCALE_ITIME_US(100 * 1000, TEST_TSEL_100, 2),
+#define TIMEGAIN_MAX 8
+};

Yours,
	-- Matti

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~