[v2,2/4] ASoC: qcom: q6afe: provide fallback for digital codec clock

When q6afe is used as a clock provider through q6afe-clocks.c, it uses
an interface for setting clocks that is not present in older firmware
versions. However, using Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE
as the codec MCLK in the device tree can be useful on older platforms
too. Provide a fallback that sets this clock using the old method when
an old firmware version is detected.

MSM8916 did not need this because of a workaround that controls this
clock directly through the GCC driver, but newer SoCs do not have this
clock in their GCC drivers because it is meant to be controlled by the
DSP.

Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
---
 sound/soc/qcom/qdsp6/q6afe.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

Thanks Otto for the patch,

On 29/10/2023 16:57, Otto Pflüger wrote:
> When q6afe is used as a clock provider through q6afe-clocks.c, it uses
> an interface for setting clocks that is not present in older firmware
> versions. However, using Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE
> as the codec MCLK in the device tree can be useful on older platforms
> too. Provide a fallback that sets this clock using the old method when
> an old firmware version is detected.
> 
> MSM8916 did not need this because of a workaround that controls this
> clock directly through the GCC driver, but newer SoCs do not have this
> clock in their GCC drivers because it is meant to be controlled by the
> DSP.
> 
> Signed-off-by: Otto Pflüger <otto.pflueger@abscue.de>
> ---
>   sound/soc/qcom/qdsp6/q6afe.c | 26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/sound/soc/qcom/qdsp6/q6afe.c b/sound/soc/qcom/qdsp6/q6afe.c
> index 91d39f6ad0bd..f14d3b366aa4 100644
> --- a/sound/soc/qcom/qdsp6/q6afe.c
> +++ b/sound/soc/qcom/qdsp6/q6afe.c
> @@ -1111,6 +1111,32 @@ int q6afe_set_lpass_clock(struct device *dev, int clk_id, int attri,
>   	struct q6afe *afe = dev_get_drvdata(dev->parent);
>   	struct afe_clk_set cset = {0,};
>   
> +	/*
> +	 * v2 clocks specified in the device tree may not be supported by the
> +	 * firmware. If this is the digital codec core clock, fall back to the
> +	 * old method for setting it.
> +	 */
> +	if (q6core_get_adsp_version() < Q6_ADSP_VERSION_2_7) {
> +		struct q6afe_port *port;
> +		struct afe_digital_clk_cfg dcfg = {0,};
> +		int ret;
> +
> +		if (clk_id != Q6AFE_LPASS_CLK_ID_INTERNAL_DIGITAL_CODEC_CORE)
> +			return -EINVAL;
> +
> +		port = q6afe_port_get_from_id(dev, PRIMARY_MI2S_RX);
> +		if (IS_ERR(port))
> +			return PTR_ERR(port);
> +
> +		dcfg.i2s_cfg_minor_version = AFE_API_VERSION_I2S_CONFIG;
> +		dcfg.clk_val = freq;
> +		dcfg.clk_root = 5;
> +		ret = q6afe_set_digital_codec_core_clock(port, &dcfg);
> +
> +		q6afe_port_put(port);

This redirection of clks looks totally confusing and hacky.
Why can not we do this from machine driver based something like this:

if (q6core_get_adsp_version() < Q6_ADSP_VERSION_2_7)
	ret = snd_soc_dai_set_sysclk(cpu_dai, LPAIF_DIG_CLK, freq, 0);



--srini
> +		return ret;
> +	}
> +
>   	cset.clk_set_minor_version = AFE_API_VERSION_CLOCK_SET;
>   	cset.clk_id = clk_id;
>   	cset.clk_freq_in_hz = freq;