Messages in this thread Patch in this message | | | Subject | Re: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal to system freq | From | Łukasz Majewski <> | Date | Sun, 3 Sep 2017 16:40:21 +0200 |
| |
Hi Fabio,
> [Sorry for the top-posting] > > > The driver currently has: > > > /* > * Hardware limitation: The bclk rate must be > * never greater than 1/5 IPG clock rate > */ > if (freq * 5 > clk_get_rate(ssi_private->clk)) { > dev_err(cpu_dai->dev, "bitclk > ipgclk/5\n"); > return -EINVAL; > } >
Unfortunately not.
This is the part of fsl_ssi_set_bclk() function which is called after fsl_ssi_set_dai_sysclk() (which sets ssi_private->bitclk_freq = freq;).
Before the aforementioned check we do have:
if (ssi_private->bitclk_freq) freq = ssi_private->bitclk_freq; else freq = params_channels(hw_params) * 32 * params_rate(hw_params);
Which assigns freq = bitclk_freq (66 MHz)
And then we break on this particular check:
66MHz * 5 > 66 MHz.
The culprit IMHO is the ssi_private->bitclk_freq = freq; in the fsl_ssi_set_dai_sysclk(), since we _should_ set SSI's IP block clock (ssi_private->clk), not the bit clock (BCLK).
This patch just quits early if it detects change, which don't need to be done.
> > Isn't this properly taking care of the clock restriction? > > ________________________________ > From: Lukasz Majewski <lukma@denx.de> > Sent: Sunday, September 3, 2017 8:05:01 AM > To: Timur Tabi; Nicolin Chen; Xiubo Li; Fabio Estevam; Liam Girdwood; Mark Brown; Jaroslav Kysela; Takashi Iwai > Cc: alsa-devel@alsa-project.org; linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org; Lukasz Majewski > Subject: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal to system freq > > The problem is visible in the following setup (on the imx6q): > "simple-audio-card" -> ssi2 -> I2S + I2C -> codec > > The function call log (simple-card probe -> CONFIG_SND_SIMPLE_CARD): > > asoc_simple_card_init_dai() @ sound/soc/generic/simple-card-utils.c > snd_soc_dai_set_sysclk() > fsl_ssi_set_dai_sysclk() @ sound/soc/fsl/fsl_ssi.c > > The last call is changing the bit clock (BCLK) frequency to SSI's IP > block clock (ipg = 66 MHz) [1]. > This is wrong, since IMX SSI block requires the I2S BCLK to be less > than 1/5 of [1]. > > As a result the driver initialization passes without any errors, but the > speaker-test test case breaks. > > This commit checks if the fsl_ssi_set_dai_sysclk() frequency passed is > not equal to [1]. > > Signed-off-by: Lukasz Majewski <lukma@denx.de> > --- > sound/soc/fsl/fsl_ssi.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c > index 173cb84..1186fa9 100644 > --- a/sound/soc/fsl/fsl_ssi.c > +++ b/sound/soc/fsl/fsl_ssi.c > @@ -809,6 +809,8 @@ static int fsl_ssi_set_dai_sysclk(struct snd_soc_dai *cpu_dai, > int clk_id, unsigned int freq, int dir) > { > struct fsl_ssi_private *ssi_private = snd_soc_dai_get_drvdata(cpu_dai); > + if (clk_get_rate(ssi_private->clk) == freq) > + return 0; > > ssi_private->bitclk_freq = freq; > > -- > 2.1.4 > >
-- Best regards,
Lukasz Majewski
-- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
| |