[alsa-devel] [PATCH v3 08/15] ASoC: tegra: Add audio mclk control through clk_out_1 and extern1
Dmitry Osipenko
digetx at gmail.com
Tue Dec 17 17:16:55 CET 2019
17.12.2019 19:12, Sowjanya Komatineni пишет:
>
> On 12/17/19 7:36 AM, Dmitry Osipenko wrote:
>> 17.12.2019 04:29, Sowjanya Komatineni пишет:
>>> 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 at 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.
>>> 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.
>> It should be better to use something "resource managed", thus
>> devm_clk_get() should be a better choice.
>>
>>> 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.
>> I'm not sure it's worth the effort to care about con_ids if implicit
>> fallback to clk_get_sys(NULL, "...") does the right thing for the audio
>> driver.
>>
>> IIRC, CCF uses variant of matching clocks by names, although I'm not
>> sure whether that applies to older stable kernels.
>>
>> [snip]
>
> Current clock driver adds EXTERN clock to lookup with dev_id as
> clk_out_1/2/3 and con_id as extern_1/2/3
>
> With this we can retrieve clock from lookup only with clk_get_sys where
> we can pass dev_id as clk_out_1/2/3 and con_id as extern_1/2/3.
>
> We cant use devm_clk_get() or clk_get() for retrieving clocks from
> lookup by passing device object from sound driver as dev_id will be diff
> and clk_find will return NULL.
Have you actually tried to test that it fails? I think it's a false
assumption.
> But with the fix of having dev_id as NULL and use only con_id to add to
> lookup, we can use resource managed APIs devm_clk_get.
>
> So was saying will fix this in clock driver as part of removing
> clk_out_1/2/3 ids and pmc init from clock driver so we can use
> devm_clk_get API in audio driver.
>
>>
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