On 14/04/2021 15:29, Spencer Olson wrote:
> On Wed, Apr 14, 2021 at 6:34 AM Ian Abbott <abbotti@xxxxxxxxx> wrote:
>>
>> On 14/04/2021 11:09, Dan Carpenter wrote:
>>> The test_ni_get_reg_value() function calls
>>> unittest(ni_get_reg_value_roffs(-1, O(0), T, 1) == -1,
>>> "check bad direct trigger arg for first reg->dest w/offs\n");
>>> The -1 is type promoted to a high positive value so src is greater than
>>> NI_NAMES_BASE. It's not clear that that was intentional.
>>> drivers/staging/comedi/drivers/tests/../ni_routes.h:269 ni_get_reg_value_roffs() warn: 'src' possible negative type promoted to high
>>
>> I agree that it appears that ni_get_reg_value_roffs() will be returning
>> -1 as expected, but for the wrong reason. I think the intention was for
>> ni_get_reg_value_roffs() to call route_register_is_valid() with src=0 in
>> this case, but it actually calls ni_route_to_register() with src=-1
>> (because -1 gets converted to 0xffffffff in the test `if (src <
>> NI_NAMES_BASE)` where NI_NAMES_BASE is defined as 0x8000u).
>>
>
> Good catch. Based on the error message that for the unittest failure,
> I would agree that my intention had been to test when src is indeed <
> NI_NAMES_BASE so that we could test for a bad direct register value.
> It does indeed look like sending in 0 for the src would have worked,
> since the first row in private table RV in ni_routes_test.c (the row
> for destination passed in as "O(0)") does not have a "register value"
> equal to 0. It would be nice to compile and test this code though,
> but I can't do it for another couple of weeks.
>
> Actually, looking a little further, I don't think that src=0 will work
> here. There is another argument for ni_get_reg_value_roffs,
> direct_reg_offset, that gets added to src before sending to
> route_register_is_valid. I think this was provided to fix an offset
> mismatch that was in the original approach to handling signal routing
> values (i.e. to provide backwards compatibility). But, I do think
> that value greater or equal to 9 will actually work.
Since that unittest() is calling ni_get_reg_value_roffs() with src=-1
and direct_reg_offset=1, and ni_get_reg_value_roffs() adds
direct_reg_offset to src if src < NI_NAMES_BASE, would setting src=0,
direct_reg_offset=0 work? I.e., like this:
unittest(ni_get_reg_value_roffs(0, O(0), T, 0) == -1,
"check bad direct trigger arg for first reg->dest
w/offs\n");
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