Date:   Mon, 16 Dec 2019 17:29:38 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <mperttunen@...dia.com>,
        <gregkh@...uxfoundation.org>, <sboyd@...nel.org>,
        <tglx@...utronix.de>, <robh+dt@...nel.org>, <mark.rutland@....com>
CC:     <allison@...utok.net>, <pdeschrijver@...dia.com>,
        <pgaikwad@...dia.com>, <mturquette@...libre.com>,
        <horms+renesas@...ge.net.au>, <Jisheng.Zhang@...aptics.com>,
        <krzk@...nel.org>, <arnd@...db.de>, <spujar@...dia.com>,
        <josephl@...dia.com>, <vidyas@...dia.com>,
        <daniel.lezcano@...aro.org>, <mmaddireddy@...dia.com>,
        <markz@...dia.com>, <devicetree@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <lgirdwood@...il.com>,
        <broonie@...nel.org>, <perex@...ex.cz>, <tiwai@...e.com>,
        <alexios.zavras@...el.com>, <alsa-devel@...a-project.org>
Subject: Re: [PATCH v3 08/15] ASoC: tegra: Add audio mclk control through
 clk_out_1 and extern1


On 12/7/19 11:20 AM, Sowjanya Komatineni wrote:
>
> 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@...dia.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.

clk_get uses device rather and dev_id will be name of this device and 
when clk_get fall back to __clk_get_sys() it still will use dev id of 
this device rather than actual dev_id that pmc clocks are added to the 
lookup. So clk_get_sys() seems to be correct to use as we can specify 
exact dev_id and con_id.

Also, clk_find retrieves clock from lookup only when it finds matching 
clock with both dev_id and con_id as pmc clocks are registered with both 
dev_id and con_id.

I see existing clock driver adds both extern and pmc clocks (clk_out) to 
lookup with same dev_id of clk_out_1/2/3 and con_id of extern1/2/3 and 
with this always extern clock will be retrieved and this is probably 
because old DT and audio driver always uses extern1 rather than actual 
clk_out_1

But this need to be fixed now as we changed to use clk_out directly 
rather than extern (even for other pmc clocks) to match actual hw design.

Will fix this as well to register pmc clocks using con_id as 
clk_out_1/2/3 in pmc driver and extern clocks using con_id of 
extern1/2/3 with dev_id being NULL so we can retrieve these clocks by 
just using con_id only using clk_get_sys as we switched to use clk_out_1 
directly as pmc clock rather than extern from DT and no longer need to 
pair pmc clocks to extern clocks.

>>
>> 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;
>>>   };
>>>

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