Re: [PATCH v3 08/15] ASoC: tegra: Add audio mclk control through clk_out_1 and extern1

[Sowjanya Komatineni <skomatineni@nvidia.com>]

On 12/7/19 6:58 AM, Dmitry Osipenko wrote:
> 06.12.2019 05:48, Sowjanya Komatineni пишет:
>> Current ASoC driver uses extern1 as cdev1 clock from Tegra30 onwards
>> through device tree.
>>
>> Actual audio mclk is clk_out_1 and to use PLLA for mclk rate control,
>> need to clk_out_1_mux parent to extern1 and extern1 parent to PLLA_OUT0.
>>
>> Currently Tegra clock driver init sets the parents and enables both
>> clk_out_1 and extern1 clocks. But these clocks parent and enables should
>> be controlled by ASoC driver.
>>
>> Clock parents can be specified in device tree using assigned-clocks
>> and assigned-clock-parents.
>>
>> To enable audio mclk, both clk_out_1 and extern1 clocks need to be
>> enabled.
>>
>> This patch configures parents for clk_out_1 and extern1 clocks if device
>> tree does not specify clock parents inorder to support old device tree
>> and controls mclk using both clk_out_1 and extern1 clocks.
>>
>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>> ---
>>   sound/soc/tegra/tegra_asoc_utils.c | 66 ++++++++++++++++++++++++++++++++++++++
>>   sound/soc/tegra/tegra_asoc_utils.h |  1 +
>>   2 files changed, 67 insertions(+)
>>
>> diff --git a/sound/soc/tegra/tegra_asoc_utils.c b/sound/soc/tegra/tegra_asoc_utils.c
>> index 536a578e9512..8e3a3740df7c 100644
>> --- a/sound/soc/tegra/tegra_asoc_utils.c
>> +++ b/sound/soc/tegra/tegra_asoc_utils.c
>> @@ -60,6 +60,7 @@ int tegra_asoc_utils_set_rate(struct tegra_asoc_utils_data *data, int srate,
>>   	data->set_mclk = 0;
>>   
>>   	clk_disable_unprepare(data->clk_cdev1);
>> +	clk_disable_unprepare(data->clk_extern1);
>>   	clk_disable_unprepare(data->clk_pll_a_out0);
>>   	clk_disable_unprepare(data->clk_pll_a);
>>   
>> @@ -89,6 +90,14 @@ int tegra_asoc_utils_set_rate(struct tegra_asoc_utils_data *data, int srate,
>>   		return err;
>>   	}
>>   
>> +	if (!IS_ERR_OR_NULL(data->clk_extern1)) {
>> +		err = clk_prepare_enable(data->clk_extern1);
>> +		if (err) {
>> +			dev_err(data->dev, "Can't enable extern1: %d\n", err);
>> +			return err;
>> +		}
>> +	}
>> +
>>   	err = clk_prepare_enable(data->clk_cdev1);
>>   	if (err) {
>>   		dev_err(data->dev, "Can't enable cdev1: %d\n", err);
>> @@ -109,6 +118,7 @@ int tegra_asoc_utils_set_ac97_rate(struct tegra_asoc_utils_data *data)
>>   	int err;
>>   
>>   	clk_disable_unprepare(data->clk_cdev1);
>> +	clk_disable_unprepare(data->clk_extern1);
>>   	clk_disable_unprepare(data->clk_pll_a_out0);
>>   	clk_disable_unprepare(data->clk_pll_a);
>>   
>> @@ -142,6 +152,14 @@ int tegra_asoc_utils_set_ac97_rate(struct tegra_asoc_utils_data *data)
>>   		return err;
>>   	}
>>   
>> +	if (!IS_ERR_OR_NULL(data->clk_extern1)) {
>> +		err = clk_prepare_enable(data->clk_extern1);
>> +		if (err) {
>> +			dev_err(data->dev, "Can't enable extern1: %d\n", err);
>> +			return err;
>> +		}
>> +	}
> Why this is needed given that clk_extern1 is either a child of MCLK or
> MCLK itself (on T20)? The child clocks are enabled when the parent is
> enabled.

For T30 and later, clk_extern1 is one of the source for clk_out_1_mux. 
clk_extern1 is in CAR and it has its own gate and mux.

As audio mclk related clocks (clk_out_1, clk_out_1_mux, and extern1) are 
moved into ASoC driver from clock driver

need to enable extern1 gate as well along with clk_out1 for T30 through 
T210.

Just FYI, extern1 enable here happens only when data->clk_extern1 is 
available which is for T30 onwards.

>>   	err = clk_prepare_enable(data->clk_cdev1);
>>   	if (err) {
>>   		dev_err(data->dev, "Can't enable cdev1: %d\n", err);
>> @@ -158,6 +176,7 @@ EXPORT_SYMBOL_GPL(tegra_asoc_utils_set_ac97_rate);
>>   int tegra_asoc_utils_init(struct tegra_asoc_utils_data *data,
>>   			  struct device *dev)
>>   {
>> +	struct clk *clk_out_1_mux;
>>   	int ret;
>>   
>>   	data->dev = dev;
>> @@ -196,6 +215,51 @@ int tegra_asoc_utils_init(struct tegra_asoc_utils_data *data,
>>   		goto err_put_pll_a_out0;
>>   	}
> In a previous patch you added fallback to EXTPERIPH when clk_get(MCLK)
> fails. This will work perfectly fine for the older kernels which have
> all clocks in the same single CaR driver, but this may not work that
> great for the newer kernels because PMC driver isn't registered early
> during boot and thus it is possible to get a legit -EPROBE_DEFER which
> shouldn't be ignored. In other words, you need to add into this patch a
> check for the error code returned by clk_get(MCLK) and fallback only for
> -EINVAL.
yeah right, will add check in next version.
>> +	/*
>> +	 * If clock parents are not set in DT, configure here to use clk_out_1
>> +	 * as mclk and extern1 as parent for Tegra30 and higher.
>> +	 */
>> +	if (!of_find_property(dev->of_node, "assigned-clock-parents", NULL) &&
>> +	    data->soc > TEGRA_ASOC_UTILS_SOC_TEGRA20) {
>> +		data->clk_extern1 = clk_get_sys("clk_out_1", "extern1");
>> +		if (IS_ERR(data->clk_extern1)) {
>> +			dev_err(data->dev, "Can't retrieve clk extern1\n");
>> +			ret = PTR_ERR(data->clk_extern1);
>> +			goto err_put_cdev1;
>> +		}
>> +
>> +		ret = clk_set_parent(data->clk_extern1, data->clk_pll_a_out0);
>> +		if (ret < 0) {
>> +			dev_err(data->dev,
>> +				"Set parent failed for clk extern1: %d\n",
>> +				ret);
>> +			goto err_put_cdev1;
>> +		}
>> +
>> +		clk_out_1_mux = clk_get_sys(NULL, "clk_out_1_mux");
> Note1: clk_get(dev, "clk_out_1_mux") should work here by letting clk
> core to fall back to the clk_get_sys() by itself. Either way should be good.
>
> Note2: devm_clk_get() could be used everywhere here. Maybe it won't hurt
> to convert tegra_asoc_utils to use managed resources to keep code a bit
> cleaner. It should be a separate patch.

OK Will add patch to use devm_clk_get() in tegra_asoc_utils_init and 
will use same for these patches

>> +		if (IS_ERR(clk_out_1_mux)) {
>> +			dev_err(data->dev, "Can't retrieve clk clk_out_1_mux\n");
>> +			ret = PTR_ERR(clk_out_1_mux);
>> +			goto err_put_cdev1;
>> +		}
>> +
>> +		ret = clk_set_parent(clk_out_1_mux, data->clk_extern1);
>> +		if (ret < 0) {
>> +			dev_err(data->dev,
>> +				"Set parent failed for clk_out_1_mux: %d\n",
>> +				ret);
>> +			clk_put(clk_out_1_mux);
>> +			goto err_put_cdev1;
>> +		}
> clk_put(clk_cdev1);
>
>> +		data->clk_cdev1 = clk_get_sys(NULL, "clk_out_1");
>> +		if (IS_ERR(data->clk_cdev1)) {
>> +			dev_err(data->dev, "Can't retrieve clk clk_out_1\n");
>> +			ret = PTR_ERR(data->clk_cdev1);
>> +			goto err_put_cdev1;
> goto err_put_pll_a_out0;
>
>> +		}
>> +	}
>> +
>>   	ret = tegra_asoc_utils_set_rate(data, 44100, 256 * 44100);
>>   	if (ret)
>>   		goto err_put_cdev1;
>> @@ -215,6 +279,8 @@ EXPORT_SYMBOL_GPL(tegra_asoc_utils_init);
>>   
>>   void tegra_asoc_utils_fini(struct tegra_asoc_utils_data *data)
>>   {
>> +	if (!IS_ERR_OR_NULL(data->clk_extern1))
>> +		clk_put(data->clk_extern1);
>>   	clk_put(data->clk_cdev1);
>>   	clk_put(data->clk_pll_a_out0);
>>   	clk_put(data->clk_pll_a);
>> diff --git a/sound/soc/tegra/tegra_asoc_utils.h b/sound/soc/tegra/tegra_asoc_utils.h
>> index 0c13818dee75..5f2b96478caf 100644
>> --- a/sound/soc/tegra/tegra_asoc_utils.h
>> +++ b/sound/soc/tegra/tegra_asoc_utils.h
>> @@ -25,6 +25,7 @@ struct tegra_asoc_utils_data {
>>   	struct clk *clk_pll_a;
>>   	struct clk *clk_pll_a_out0;
>>   	struct clk *clk_cdev1;
>> +	struct clk *clk_extern1;
>>   	int set_baseclock;
>>   	int set_mclk;
>>   };
>>