lkml.org 
[lkml]   [2020]   [Oct]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 20/25] ASoC: sun8i-codec: Protect the clock rate while streams are open
On Mon, Oct 5, 2020 at 8:01 PM Maxime Ripard <maxime@cerno.tech> wrote:
>
> On Wed, Sep 30, 2020 at 09:11:43PM -0500, Samuel Holland wrote:
> > The codec's clock input is shared among all AIFs, and shared with other
> > audio-related hardware in the SoC, including I2S and SPDIF controllers.
> > To ensure sample rates selected by userspace or by codec2codec DAI links
> > are maintained, the clock rate must be protected while it is in use.
> >
> > Signed-off-by: Samuel Holland <samuel@sholland.org>
> > ---
> > sound/soc/sunxi/sun8i-codec.c | 25 ++++++++++++++++++++++---
> > 1 file changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/sound/soc/sunxi/sun8i-codec.c b/sound/soc/sunxi/sun8i-codec.c
> > index 501af64d43a0..86065bee7cd3 100644
> > --- a/sound/soc/sunxi/sun8i-codec.c
> > +++ b/sound/soc/sunxi/sun8i-codec.c
> > @@ -416,27 +416,32 @@ static int sun8i_codec_get_lrck_div_order(unsigned int slots,
> > unsigned int div = slots * slot_width;
> >
> > if (div < 16 || div > 256)
> > return -EINVAL;
> >
> > return order_base_2(div);
> > }
> >
> > +static unsigned int sun8i_codec_get_sysclk_rate(unsigned int sample_rate)
> > +{
> > + return sample_rate % 4000 ? 22579200 : 24576000;
> > +}
> > +
> > static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
> > struct snd_pcm_hw_params *params,
> > struct snd_soc_dai *dai)
> > {
> > struct sun8i_codec *scodec = snd_soc_dai_get_drvdata(dai);
> > struct sun8i_codec_aif *aif = &scodec->aifs[dai->id];
> > unsigned int sample_rate = params_rate(params);
> > unsigned int slots = aif->slots ?: params_channels(params);
> > unsigned int slot_width = aif->slot_width ?: params_width(params);
> > - unsigned int sysclk_rate = clk_get_rate(scodec->clk_module);
> > - int lrck_div_order, word_size;
> > + unsigned int sysclk_rate = sun8i_codec_get_sysclk_rate(sample_rate);
> > + int lrck_div_order, ret, word_size;
> > u8 bclk_div;
> >
> > /* word size */
> > switch (params_width(params)) {
> > case 8:
> > word_size = 0x0;
> > break;
> > case 16:
> > @@ -466,17 +471,30 @@ static int sun8i_codec_hw_params(struct snd_pcm_substream *substream,
> > (lrck_div_order - 4) << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_DIV);
> >
> > /* BCLK divider (SYSCLK/BCLK ratio) */
> > bclk_div = sun8i_codec_get_bclk_div(sysclk_rate, lrck_div_order, sample_rate);
> > regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
> > SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV_MASK,
> > bclk_div << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_DIV);
> >
> > - if (!aif->open_streams) {
> > + /* SYSCLK rate */
> > + if (aif->open_streams) {
> > + ret = clk_set_rate(scodec->clk_module, sysclk_rate);
> > + if (ret < 0)
> > + return ret;
> > + } else {
> > + ret = clk_set_rate_exclusive(scodec->clk_module, sysclk_rate);
>
> It's not really clear to me why we wouldn't want to always protect the
> clock rate here?

I believe the intention is to allow a window, i.e. when no audio
blocks are running,
when it is possible to switch between sample rate families?

ChenYu

> > + if (ret == -EBUSY)
> > + dev_err(dai->dev, "%s: clock is busy! Sample rate %u Hz "
> > + "conflicts with other audio streams.\n",
>
> This string creates a checkpatch warning.
>
> Maxime

\
 
 \ /
  Last update: 2020-10-05 15:17    [W:0.056 / U:0.796 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site