Hi

On Thu, Apr 18, 2019 at 02:37:03AM +0000, S.j. Wang wrote:

...

...

Here:

...

• /* Does not support cases: Tsout > 8.125 * Tsin */
  

• if (inrate * 8 > 65 * outrate)
  

Though it might not matter any more (see my last comments), it should be "inrate > 8.125 * outrate" in the comments.

...

...

...

•         return -EINVAL;
  

And here:

...

• ret = fsl_asrc_sel_proc(inrate, outrate, &pre_proc, &post_proc);
  

• if (ret) {
  

•         pair_err("No supported pre-processing options\n");
  

•         return ret;
  

• }
  

Instead of a general message, I was thinking of a more specific one by telling users that the ratio between the two rates isn't supported -- something similar to what I suggested previously:

    pair_err("Does not support %d (input) > 8.125 * %d (output)\n",
             outrate, inrate);

...

In fsl_asrc_sel_proc, we can't call the pair_err for there is no struct fsl_asrc_pair *pair in the argument. Do you think we need to add this argument?

I's thinking of adding it to the top of fsl_asrc_config_pair() as a part of inrate-outrate-validation, however, I found that actually we already have a similar check in the early routine: if ((outrate > 8000 && outrate < 30000) && (outrate/inrate > 24 || inrate/outrate > 8)) { pair_err("exceed supported ratio range [1/24, 8] for \ inrate/outrate: %d/%d\n", inrate, outrate); return -EINVAL; }

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)) {

However, we do need a patch to fix a potential rounding issue:

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

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

Should fix the missing whitespace also. And it will be needed to send to stable kernel too. Will you help submit a change?

Thanks