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Message-ID: <CAA+D8APivJWD-AqwmQ-mtcr=ZHot5rfA8FRWF2+p-_mq5BGxHA@mail.gmail.com>
Date: Thu, 16 Jan 2025 12:01:13 +0800
From: Shengjiu Wang <shengjiu.wang@...il.com>
To: Stefan Eichenberger <eichest@...il.com>
Cc: abelvesa@...nel.org, peng.fan@....com, mturquette@...libre.com,
sboyd@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
kernel@...gutronix.de, festevam@...il.com, shengjiu.wang@....com,
francesco.dolcini@...adex.com, linux-clk@...r.kernel.org, imx@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Stefan Eichenberger <stefan.eichenberger@...adex.com>, stable@...r.kernel.org
Subject: Re: [PATCH v1] clk: imx: imx8-acm: fix flags for acm clocks
On Wed, Jan 15, 2025 at 6:39 PM Stefan Eichenberger <eichest@...il.com> wrote:
>
> On Wed, Jan 15, 2025 at 05:14:09PM +0800, Shengjiu Wang wrote:
> > On Wed, Jan 15, 2025 at 4:33 PM Stefan Eichenberger <eichest@...il.com> wrote:
> > >
> > > Hi Shengjiu Wang,
> > >
> > > On Tue, Jan 14, 2025 at 12:58:24PM +0100, Stefan Eichenberger wrote:
> > > > Hi Shengjiu Wang,
> > > >
> > > > On Tue, Jan 14, 2025 at 03:49:10PM +0800, Shengjiu Wang wrote:
> > > > > On Mon, Jan 13, 2025 at 5:54 PM Stefan Eichenberger <eichest@...il.com> wrote:
> > > > > >
> > > > > > From: Stefan Eichenberger <stefan.eichenberger@...adex.com>
> > > > > >
> > > > > > Currently, the flags for the ACM clocks are set to 0. This configuration
> > > > > > causes the fsl-sai audio driver to fail when attempting to set the
> > > > > > sysclk, returning an EINVAL error. The following error messages
> > > > > > highlight the issue:
> > > > > > fsl-sai 59090000.sai: ASoC: error at snd_soc_dai_set_sysclk on 59090000.sai: -22
> > > > > > imx-hdmi sound-hdmi: failed to set cpu sysclk: -22
> > > > >
> > > > > The reason for this error is that the current clock parent can't
> > > > > support the rate
> > > > > you require (I think you want 11289600).
> > > > >
> > > > > We can configure the dts to provide such source, for example:
> > > > >
> > > > > &sai5 {
> > > > > + assigned-clocks = <&acm IMX_ADMA_ACM_SAI5_MCLK_SEL>,
> > > > > + <&acm IMX_ADMA_ACM_AUD_CLK1_SEL>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_PLL>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_SLV_BUS>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_MST_BUS>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_PLL>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_SLV_BUS>,
> > > > > + <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_MST_BUS>,
> > > > > + <&sai5_lpcg 0>;
> > > > > + assigned-clock-parents = <&aud_pll_div0_lpcg 0>, <&aud_rec1_lpcg 0>;
> > > > > + assigned-clock-rates = <0>, <0>, <786432000>, <49152000>, <12288000>,
> > > > > + <722534400>, <45158400>, <11289600>,
> > > > > + <49152000>;
> > > > > status = "okay";
> > > > > };
> > > > >
> > > > > Then your case should work.
> > > > >
> > > > > >
> > > > > > By setting the flag CLK_SET_RATE_NO_REPARENT, we signal that the ACM
> > > > >
> > > > > I don't think CLK_SET_RATE_NO_REPARENT is a good choice. which will cause
> > > > > the driver don't get an error from clk_set_rate().
> > > >
> > > > Thanks for the proposal, I will try it out tomorrow. Isn't this a
> > > > problem if other SAIs use the same clock source but with different
> > > > rates?
> > > >
> > > > If we have to define fixed rates in the DTS or else the clock driver
> > > > will return an error, isn't that a problem? Maybe I should change the
> > > > sai driver so that it ignores the failure and just takes the rate
> > > > configured? In the end audio works, even if it can't set the requested
> > > > rate.
> > >
> > > The following clock tree change would allow the driver to work
> > > in our scenario:
> > > &sai5 {
> > > assigned-clocks = <&acm IMX_ADMA_ACM_SAI5_MCLK_SEL>,
> > > <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_PLL>;
> > > assigned-clock-parents = <&aud_pll_div1_lpcg 0>;
> > > assigned-clock-rates = <0>, <11289600>;
> > > };
> >
> > In which we configure PLL_0 for 48KHz series (8kHz/16kHz/32kHz/48kHz),
> > PLL_1 for 44kHz series (11kHz/22kHz/44kHz),
> > which should fit for most audio requirements.
> >
> > >
> > > However, this means we have to switch the parent clock to the audio pll
> > > 1. For the simple setup with two SAIs, one for analog audio and one for
> > > HDMI this wouldn't be a problem. But I'm not sure if this is a good
> > > solution if a customer would add a third SAI which requires again a
> > > different parent clock rate.
> >
> > We won't change the PLL's rate in the driver, so as PLL_0 for 48kHz,
> > PLL_1 for 44kHz, even with a third SAI or more, they should work.
> >
> > >
> > > One potential solution could be that the SAI driver tries to first
> > > derive the clock from the current parent and only if this fails it tries
> > > to modify its parent clock. What do you think about this solution?
> > >
>
> I did some more testing and I'm still not happy with the current
> solution. The problem is that if we change the SAI5 mclk clock parent it
> can either support the 44kHz series or the 48kHz series. However, in the
> case of HDMI we do not know in advance what the user wants.
>
> This means when testing either this works:
> speaker-test -D hw:2,0 -r 48000 -c 2
> or this works:
> speaker-test -D hw:2,0 -r 44100 -c 2
> With:
> card 2: imxaudiohdmitx [imx-audio-hdmi-tx], device 0: i.MX HDMI i2s-hifi-0 [i.MX HDMI i2s-hifi-0]
Are you using the setting below? then should not either, should both works
&sai5 {
+ assigned-clocks = <&acm IMX_ADMA_ACM_SAI5_MCLK_SEL>,
+ <&acm IMX_ADMA_ACM_AUD_CLK1_SEL>,
+ <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_PLL>,
+ <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_SLV_BUS>,
+ <&clk IMX_SC_R_AUDIO_PLL_0 IMX_SC_PM_CLK_MST_BUS>,
+ <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_PLL>,
+ <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_SLV_BUS>,
+ <&clk IMX_SC_R_AUDIO_PLL_1 IMX_SC_PM_CLK_MST_BUS>,
+ <&sai5_lpcg 0>;
+ assigned-clock-parents = <&aud_pll_div0_lpcg 0>, <&aud_rec1_lpcg 0>;
+ assigned-clock-rates = <0>, <0>, <786432000>, <49152000>, <12288000>,
+ <722534400>, <45158400>, <11289600>,
+ <49152000>;
status = "okay";
};
best regards
Shengjiu Wang
>
> If I on the other hand avoid that fsl_sai_set_mclk_rate is called by
> patching imx-hdmi.c. I can make both rates work with the standard clock
> settings. So I wonder if calling snd_soc_dai_set_sysclk is really
> necessary for the i.MX8?
> diff --git a/sound/soc/fsl/imx-hdmi.c b/sound/soc/fsl/imx-hdmi.c
> index f9cec6f0aecd..7d8aa58645b7 100644
> --- a/sound/soc/fsl/imx-hdmi.c
> +++ b/sound/soc/fsl/imx-hdmi.c
> @@ -92,15 +92,6 @@ static int imx_hdmi_hw_params(struct snd_pcm_substream *substream,
> u32 slot_width = data->cpu_priv.slot_width;
> int ret;
>
> - /* MCLK always is (256 or 192) * rate. */
> - ret = snd_soc_dai_set_sysclk(cpu_dai, data->cpu_priv.sysclk_id[tx],
> - 8 * slot_width * params_rate(params),
> - tx ? SND_SOC_CLOCK_OUT : SND_SOC_CLOCK_IN);
> - if (ret && ret != -ENOTSUPP) {
> - dev_err(dev, "failed to set cpu sysclk: %d\n", ret);
> - return ret;
> - }
> -
> ret = snd_soc_dai_set_tdm_slot(cpu_dai, 0, 0, 2, slot_width);
> if (ret && ret != -ENOTSUPP) {
> dev_err(dev, "failed to set cpu dai tdm slot: %d\n", ret);
>
> Regards,
> Stefan
>
>
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