linux-kernel - Re: [PATCH V2 1/2] ASoC: fsl_asrc: replace the process

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Message-ID: <VE1PR04MB6479AF6501388845572EC268E3250@VE1PR04MB6479.eurprd04.prod.outlook.com>
Date:   Wed, 17 Apr 2019 09:04:01 +0000
From:   "S.j. Wang" <shengjiu.wang@....com>
To:     Nicolin Chen <nicoleotsuka@...il.com>
CC:     "timur@...nel.org" <timur@...nel.org>,
        "Xiubo.Lee@...il.com" <Xiubo.Lee@...il.com>,
        "festevam@...il.com" <festevam@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 1/2] ASoC: fsl_asrc: replace the process_option table
 with function

Hi

> 
> 
> 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

Thanks for reviewing, will send v3.