Re: max1363 : Warnings from iio_sanity_check_avail_scan_masks()

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 23 Apr 2025 17:23:28 -0300
Fabio Estevam <festevam@gmail.com> wrote:

> Hi,
> 
> After upgrading the kernel from 6.1 to 6.12 (also tested with
> linux-next), I started seeing the following warnings on a board
> populated with a Maxim MAX11601 ADC:
> 
> [    1.554029] max1363 1-0064: available_scan_mask 8 subset of 0. Never used
> [    1.563627] max1363 1-0064: available_scan_mask 9 subset of 0. Never used
> [    1.570439] max1363 1-0064: available_scan_mask 10 subset of 0. Never used
> [    1.577328] max1363 1-0064: available_scan_mask 11 subset of 0. Never used
> [    1.584226] max1363 1-0064: available_scan_mask 12 subset of 0. Never used
> [    1.591119] max1363 1-0064: available_scan_mask 13 subset of 0. Never used
> [    1.598013] max1363 1-0064: available_scan_mask 8 subset of 1. Never used
> [    1.604817] max1363 1-0064: available_scan_mask 9 subset of 1. Never used
> [    1.611623] max1363 1-0064: available_scan_mask 10 subset of 1. Never used
> [    1.618516] max1363 1-0064: available_scan_mask 11 subset of 1. Never used
> [    1.625403] max1363 1-0064: available_scan_mask 12 subset of 1. Never used
> [    1.632293] max1363 1-0064: available_scan_mask 13 subset of 1. Never used
> [    1.639201] max1363 1-0064: available_scan_mask 8 subset of 2. Never used
> [    1.646002] max1363 1-0064: available_scan_mask 9 subset of 2. Never used
> [    1.652802] max1363 1-0064: available_scan_mask 10 subset of 2. Never used
> [    1.659691] max1363 1-0064: available_scan_mask 11 subset of 2. Never used
> [    1.666582] max1363 1-0064: available_scan_mask 12 subset of 2. Never used
> [    1.673478] max1363 1-0064: available_scan_mask 13 subset of 2. Never used
> [    1.680382] max1363 1-0064: available_scan_mask 8 subset of 3. Never used
> [    1.687183] max1363 1-0064: available_scan_mask 9 subset of 3. Never used
> [    1.693984] max1363 1-0064: available_scan_mask 10 subset of 3. Never used
> [    1.700871] max1363 1-0064: available_scan_mask 11 subset of 3. Never used
> [    1.707758] max1363 1-0064: available_scan_mask 12 subset of 3. Never used
> [    1.714645] max1363 1-0064: available_scan_mask 13 subset of 3. Never used
> [    1.721532] max1363 1-0064: available_scan_mask 8 subset of 4. Never used
> [    1.728332] max1363 1-0064: available_scan_mask 9 subset of 4. Never used
> [    1.735134] max1363 1-0064: available_scan_mask 10 subset of 4. Never used
> [    1.742022] max1363 1-0064: available_scan_mask 11 subset of 4. Never used
> [    1.748908] max1363 1-0064: available_scan_mask 12 subset of 4. Never used
> [    1.755796] max1363 1-0064: available_scan_mask 13 subset of 4. Never used
> [    1.762683] max1363 1-0064: available_scan_mask 8 subset of 5. Never used
> [    1.769484] max1363 1-0064: available_scan_mask 9 subset of 5. Never used
> [    1.776283] max1363 1-0064: available_scan_mask 10 subset of 5. Never used
> [    1.783171] max1363 1-0064: available_scan_mask 11 subset of 5. Never used
> [    1.790065] max1363 1-0064: available_scan_mask 12 subset of 5. Never used
> [    1.796955] max1363 1-0064: available_scan_mask 13 subset of 5. Never used
> [    1.803846] max1363 1-0064: available_scan_mask 7 subset of 6. Never used
> [    1.810646] max1363 1-0064: available_scan_mask 8 subset of 6. Never used
> [    1.817446] max1363 1-0064: available_scan_mask 9 subset of 6. Never used
> [    1.824246] max1363 1-0064: available_scan_mask 10 subset of 6. Never used
> [    1.831164] max1363 1-0064: available_scan_mask 11 subset of 6. Never used
> [    1.838053] max1363 1-0064: available_scan_mask 12 subset of 6. Never used
> [    1.844941] max1363 1-0064: available_scan_mask 13 subset of 6. Never used
> [    1.851828] max1363 1-0064: available_scan_mask 8 subset of 7. Never used
> [    1.858627] max1363 1-0064: available_scan_mask 9 subset of 7. Never used
> [    1.865424] max1363 1-0064: available_scan_mask 10 subset of 7. Never used
> [    1.872311] max1363 1-0064: available_scan_mask 11 subset of 7. Never used
> [    1.879197] max1363 1-0064: available_scan_mask 12 subset of 7. Never used
> [    1.886084] max1363 1-0064: available_scan_mask 13 subset of 7. Never used
> [    1.892971] max1363 1-0064: available_scan_mask 9 subset of 8. Never used
> [    1.899771] max1363 1-0064: available_scan_mask 10 subset of 8. Never used
> [    1.906657] max1363 1-0064: available_scan_mask 11 subset of 8. Never used
> [    1.913544] max1363 1-0064: available_scan_mask 12 subset of 8. Never used
> [    1.920430] max1363 1-0064: available_scan_mask 13 subset of 8. Never used
> [    1.927322] max1363 1-0064: available_scan_mask 10 subset of 9. Never used
> [    1.934210] max1363 1-0064: available_scan_mask 11 subset of 9. Never used
> [    1.941096] max1363 1-0064: available_scan_mask 12 subset of 9. Never used
> [    1.947980] max1363 1-0064: available_scan_mask 13 subset of 9. Never used
> [    1.954867] max1363 1-0064: available_scan_mask 11 subset of 10. Never used
> [    1.961841] max1363 1-0064: available_scan_mask 12 subset of 10. Never used
> [    1.968815] max1363 1-0064: available_scan_mask 13 subset of 10. Never used
> [    1.975789] max1363 1-0064: available_scan_mask 12 subset of 11. Never used
> [    1.982762] max1363 1-0064: available_scan_mask 13 subset of 11. Never used
> [    1.989735] max1363 1-0064: available_scan_mask 13 subset of 12. Never used
> 
> What is the correct way to fix these warnings?

Ah.  I think we have an order of modes bug.. Later entries should never be a subset
of earlier ones and we only recently added a sanity check on that.

static const enum max1363_modes max11607_mode_list[] = {
	_s0, _s1, _s2, _s3,
	s0to1, s0to2, s0to3,
	s2to3,
	d0m1, d2m3, d1m0, d3m2,
	d0m1to2m3, d1m0to3m2,
};

Is used to build available_scan_masks for this device.
I'm failing to correlate with the warnings but clearly s2to3 is a subset of s0to3
channels 2,3 vs 0,1,2,3

In general we should do a few things in here.

Reorder the enum max1363 to reflect the subset rule correctly (may be
fine from a quick look).
Use that to set the entries in the max1363_mode_table.
(I think it's fine today but we can enforce that).

Finally ensure we obey the rules for the individual mode_list tables.

With that stuff fixed we should remove possibility of enabling more
channels than strictly necessary (which is what that print is moaning about.)

As a trivial test, just reorder max11607_mode_list[] it might fix your warning.
I'm a bit unconvinced that this is the only issue though as we should have
only seen 7 is a subset of 6.

If you can dump the available_modes table that is generated that might let
us see what is causing there to be so many warnings.

Jonathan





  
> 
> Thanks,
> 
> Fabio Estevam