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SubjectRe: [PATCH V2 1/2] ASoC: fsl_asrc: replace the process_option table with function
On Thu, Apr 11, 2019 at 09:39:06AM +0000, S.j. Wang wrote:

> +/*
> + * Select the pre-processing and post-processing options

By aligning with other function comments:
/**
* Select the pre-processing and post-processing options

> + *
> + * Fsin: input sample rate
> + * Fsout: output sample rate

I would suggest to use inrate and outrate to keep naming consistent.

> + * pre_proc: return value for pre-processing option
> + * post_proc: return value for post-processing option
> + */
> +static int fsl_asrc_sel_proc(int Fsin, int Fsout, int *pre_proc, int *post_proc)
> +{
> + bool det_out_op2_cond;
> + bool det_out_op0_cond;

By looking at the comments below. Probably better to rename them
bool post_proc_cond2, post_proc_cond0;

> + /* Codition for selection of post-processing */

"Codition" -> "Conditions"

> + det_out_op2_cond = (((Fsin * 15 > Fsout * 16) & (Fsout < 56000)) |
> + ((Fsin > 56000) & (Fsout < 56000)));

Combining Daniel's comments + indentation alignment:
det_out_op2_cond = (Fsin * 15 > Fsout * 16 && Fsout < 56000) ||
(Fsin > 56000 && Fsout < 56000);

> + det_out_op0_cond = (Fsin * 23 < Fsout * 8);
> +
> + /*
> + * unsupported case: Tsout>16.125*Tsin, and Tsout>8.125*Tsin.

Funny thing is that there'd be no point in checking the 16.125, if
Tsout is bigger than 8.125 times of Tsin, i.e. only one condition:
Tsout > 8.125 * Tsin

> + * Tsout>16.125*Tsin -> Fsin * 8 > 129 * Fsout
> + * Tsout>8.125*Tsin -> Fsin * 8 > 65 * Fsout
> + * Tsout>4.125*Tsin -> Fsin * 8 > 33 * Fsout
> + * Tsout>1.875*Tsin -> Fsin * 8 > 15 * Fsout

Took me a while to understand what it is saying....

Better to write like this:
/* Does not support cases: Tsout > 8.125 * Tsin */
if (Fsin * 8 > 65 * Fsout) {
pair_err("Does not support %d > 8.125 * %d\n", Fsout, Fsin);
return -EINVAL;
}

/* Otherwise, select pre_proc between [0, 2] */
if (Fsin * 8 > 33 * Fsout)
> + *pre_proc = 2;
> + else if (Fsin * 8 > 15 * Fsout) {
> + if (Fsin > 152000)
> + *pre_proc = 2;
> + else
> + *pre_proc = 1;
> + } else if (Fsin < 76000)
> + *pre_proc = 0;
> + else if (Fsin > 152000)
> + *pre_proc = 2;
> + else
> + *pre_proc = 1;

<== Would look better by moving post_cond calculations here.

> + if (det_out_op2_cond)
> + *post_proc = 2;
> + else if (det_out_op0_cond)
> + *post_proc = 0;
> + else
> + *post_proc = 1;

And we could remove this check below:
> + /* unsupported options */
> + if (*pre_proc == 4 || *pre_proc == 5)
> + return -EINVAL;

So basically we are doing:
1) Error out unsupported cases
2) Select pre_proc
3) Calculate conditions for post_proc
4) Select post_proc

Thanks

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