Hi

On Thu, Apr 18, 2019 at 09:37:06AM +0000, S.j. Wang wrote:

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And this is according to IMX6DQRM: Limited support for the case when output sampling rates is between 8kHz and 30kHz. The limitation is the supported ratio (Fsin/Fsout) range as between 1/24 to 8

This should cover your 8.125 condition already, even if having an outrate range between [8KHz, 30KHz] check, since an outrate above 30KHz will not have an inrate bigger than 8.125 times of it, given the maximum input rate is 192KHz.

So I think that we can just drop that 8.125 condition from your change and there's no need to error out any more.

No, if outrate=8kHz, inrate > 88.2kHz, these cases are not supported. This is not covered by

    if ((outrate > 8000 && outrate < 30000) &&
        (outrate/inrate > 24 || inrate/outrate > 8)) {

Good catch. The range should be [8KHz, 30KHz] vs. (8KHz, 32KHz) in the code. Then I think the fix should be at both lines:

•     if ((outrate > 8000 && outrate < 30000) &&
  

•         (outrate/inrate > 24 || inrate/outrate > 8)) {
  

•     if ((outrate >= 8000 && outrate =< 30000) &&
  

•         (outrate > 24 * inrate || inrate > 8 * outrate)) {
  
  

Overall, I think we should fix this instead of adding an extra one, since it is very likely saying the same thing.

Actually if outrate < 8kHz, there will be issue too.

Here is the thing, the RM doesn't explicitly state that ASRC can support a lower output sample rate than 8KHz. And I actually had a concern when reviewing your PATCH-2, as the table of supported output sample rate no longer matches RM.

If you've verified a lower output sample rate working solid with the process_option function, that means our driver can go beyond the limitation mentioned in the RM, then I believe [8KHz, 32KHz] should be updated too -- that says we can do:

•   if ((outrate > 8000 && outrate < 30000) &&
  

•       (outrate/inrate > 24 || inrate/outrate > 8)) {
  

•   if ((outrate >= 5512 && outrate =< 30000) &&
  

•       (outrate > 24 * inrate || inrate > 8 * outrate)) {
  
  

Actually "ourate > 24 * inrate" is kind of pointless for range [5KHz, 32KHz] but we can keep it since it matches RM.

Ok, will send v4.

Best regards Wang shengjiu