Date:   Thu, 16 Mar 2017 10:49:20 +0200
From:   Daniel Baluta <daniel.baluta@...il.com>
To:     Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:     Daniel Baluta <daniel.baluta@....com>, alsa-devel@...a-project.org,
        shengjiu.wang@...escale.com, patches@...nsource.wolfsonmicro.com,
        Liam Girdwood <lgirdwood@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>, viorel.suman@....com,
        mihai.serban@....com, Takashi Iwai <tiwai@...e.com>
Subject: Re: [alsa-devel] [RFC PATCH 1/2] ASoC: codec: wm8960: Refactor sysclk
 freq search

On Wed, Mar 15, 2017 at 6:22 PM, Charles Keepax
<ckeepax@...nsource.wolfsonmicro.com> wrote:
> On Wed, Mar 15, 2017 at 05:33:05PM +0200, Daniel Baluta wrote:
>> Add a separate function for finding (sysclk, lrclk, bclk)
>> when the clock is auto or mclk. This makes code easier to
>> read and reduces the indentation level in wm8960_configure_clocking.
>>
>> Signed-off-by: Daniel Baluta <daniel.baluta@....com>
>> ---
>>  sound/soc/codecs/wm8960.c | 82 +++++++++++++++++++++++++++++++++++------------
>>  1 file changed, 62 insertions(+), 20 deletions(-)
>>
>> diff --git a/sound/soc/codecs/wm8960.c b/sound/soc/codecs/wm8960.c
>> index 3bf081a..cb2ff2d 100644
>> --- a/sound/soc/codecs/wm8960.c
>> +++ b/sound/soc/codecs/wm8960.c
>> @@ -604,12 +604,71 @@ static const int bclk_divs[] = {
>>       120, 160, 220, 240, 320, 320, 320
>>  };
>>
>> +/**
>> + * wm8960_configure_sysclk - checks if there is a sysclk frequency available
>> + *   The sysclk must be chosen such that:
>> + *           - sysclk     = MCLK / sysclk_divs
>> + *           - lrclk      = sysclk / dac_divs
>> + *           - 10 * bclk  = sysclk / bclk_divs
>> + *
>> + * @wm8960_priv: wm8960 codec private data
>> + * @mclk: MCLK used to derive sysclk
>> + * @_i: sysclk_divs index for found sysclk
>> + * @_j: dac_divs index for found lrclk
>> + * @_k: bclk_divs index for found bclk
>> + *
>> + * Returns:
>> + * -1, in case no sysclk frequency available found
>> + *  0, in case an exact match is found. See @_i, @_j, @_k
>> + *
>> + */
>> +int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk,
>> +                   int *_i, int *_j, int *_k)
>
> This probably wants to be static.

You are right. Will fix in next version.

>
>> +{
>> +     int sysclk, bclk, lrclk;
>> +     int i, j, k;
>> +     int diff;
>> +
>> +     bclk = wm8960->bclk;
>> +     lrclk = wm8960->lrclk;
>> +
>> +     /* check if the sysclk frequency is available. */
>> +     for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) {
>> +             if (sysclk_divs[i] == -1)
>> +                     continue;
>> +             sysclk = mclk / sysclk_divs[i];
>> +             for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) {
>> +                     if (sysclk != dac_divs[j] * lrclk)
>> +                             continue;
>> +                     for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k) {
>> +                             diff = sysclk - bclk * bclk_divs[k] / 10;
>> +                             if (diff == 0) {
>> +                                     *_i = i;
>> +                                     *_j = j;
>> +                                     *_k = k;
>
> I would be tempted to move these ...
>
>> +                                     break;
>> +                             }
>> +                     }
>> +                     if (k != ARRAY_SIZE(bclk_divs))
>> +                             break;
>> +             }
>> +             if (j != ARRAY_SIZE(dac_divs))
>> +                     break;
>> +     }
>> +
>> +     if (i != ARRAY_SIZE(sysclk_divs))
>> +             return 0;
>> +
>
> Down here and give _i, _j, _k slightly more descriptive names, I
> know the original code didn't have great names either but might
> as well make things a bit nicer as we are factoring it out.

Ok. This makes sense.

>
>> +     return -1;
>> +}
>> +
>>  static int wm8960_configure_clocking(struct snd_soc_codec *codec)
>>  {
>>       struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
>>       int sysclk, bclk, lrclk, freq_out, freq_in;
>>       u16 iface1 = snd_soc_read(codec, WM8960_IFACE1);
>>       int i, j, k;
>> +     int ret;
>>
>>       if (!(iface1 & (1<<6))) {
>>               dev_dbg(codec->dev,
>> @@ -643,27 +702,10 @@ static int wm8960_configure_clocking(struct snd_soc_codec *codec)
>>       }
>>
>>       if (wm8960->clk_id != WM8960_SYSCLK_PLL) {
>> -             /* check if the sysclk frequency is available. */
>> -             for (i = 0; i < ARRAY_SIZE(sysclk_divs); ++i) {
>> -                     if (sysclk_divs[i] == -1)
>> -                             continue;
>> -                     sysclk = freq_out / sysclk_divs[i];
>> -                     for (j = 0; j < ARRAY_SIZE(dac_divs); ++j) {
>> -                             if (sysclk != dac_divs[j] * lrclk)
>> -                                     continue;
>> -                             for (k = 0; k < ARRAY_SIZE(bclk_divs); ++k)
>> -                                     if (sysclk == bclk * bclk_divs[k] / 10)
>> -                                             break;
>> -                             if (k != ARRAY_SIZE(bclk_divs))
>> -                                     break;
>> -                     }
>> -                     if (j != ARRAY_SIZE(dac_divs))
>> -                             break;
>> -             }
>> -
>> -             if (i != ARRAY_SIZE(sysclk_divs)) {
>> +             ret = wm8960_configure_sysclk(wm8960, freq_out, &i, &j, &k);
>> +             if (ret == 0)
>>                       goto configure_clock;
>> -             } else if (wm8960->clk_id != WM8960_SYSCLK_AUTO) {
>> +             else if (wm8960->clk_id != WM8960_SYSCLK_AUTO) {
>
> If one clause of the if has brackets the other should too.

Ok.

thanks,
Daniel.

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