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Message-ID: <3d8f23ce-1864-4cef-9895-209aff599bfa@salutedevices.com>
Date: Tue, 19 Mar 2024 03:35:14 +0300
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Subject: Re: [PATCH 13/25] ASoC: dt-bindings: meson: axg-pdm: document
 'sysrate' property
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To: Jerome Brunet <jbrunet@baylibre.com>
CC: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>, Neil Armstrong
	<neil.armstrong@linaro.org>, Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>, Rob Herring <robh@kernel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley
	<conor+dt@kernel.org>, Philipp Zabel <p.zabel@pengutronix.de>, Kevin Hilman
	<khilman@baylibre.com>, Martin Blumenstingl
	<martin.blumenstingl@googlemail.com>, Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Linus Walleij <linus.walleij@linaro.org>,
	Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
	<linux-amlogic@lists.infradead.org>, <linux-clk@vger.kernel.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <alsa-devel@alsa-project.org>,
	<linux-sound@vger.kernel.org>, <linux-gpio@vger.kernel.org>,
	<kernel@salutedevices.com>
References: <20240314232201.2102178-1-jan.dakinevich@salutedevices.com>
 <20240314232201.2102178-14-jan.dakinevich@salutedevices.com>
 <ca80caab-2664-4797-a222-e14537eea440@linaro.org>
 <1jil1nhjwd.fsf@starbuckisacylon.baylibre.com>
 <6feba9ff-8bbf-4494-93f0-732679bc4032@salutedevices.com>
 <1j1q87hkq2.fsf@starbuckisacylon.baylibre.com>
From: Jan Dakinevich <jan.dakinevich@salutedevices.com>
In-Reply-To: <1j1q87hkq2.fsf@starbuckisacylon.baylibre.com>
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On 3/18/24 13:55, Jerome Brunet wrote:
> 
> On Sun 17 Mar 2024 at 18:52, Jan Dakinevich <jan.dakinevich@salutedevices.com> wrote:
> 
>> On 3/15/24 13:22, Jerome Brunet wrote:
>>>
>>> On Fri 15 Mar 2024 at 11:00, Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
>>>
>>>> On 15/03/2024 00:21, Jan Dakinevich wrote:
>>>>> This option allow to redefine the rate of DSP system clock.
>>>>
>>>> And why is it suitable for bindings? Describe the hardware, not what you
>>>> want to do in the driver.
>>>>
>>>>>
>>>>> Signed-off-by: Jan Dakinevich <jan.dakinevich@salutedevices.com>
>>>>> ---
>>>>>  Documentation/devicetree/bindings/sound/amlogic,axg-pdm.yaml | 4 ++++
>>>>>  1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/sound/amlogic,axg-pdm.yaml b/Documentation/devicetree/bindings/sound/amlogic,axg-pdm.yaml
>>>>> index df21dd72fc65..d2f23a59a6b6 100644
>>>>> --- a/Documentation/devicetree/bindings/sound/amlogic,axg-pdm.yaml
>>>>> +++ b/Documentation/devicetree/bindings/sound/amlogic,axg-pdm.yaml
>>>>> @@ -40,6 +40,10 @@ properties:
>>>>>    resets:
>>>>>      maxItems: 1
>>>>>  
>>>>> +  sysrate:
>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>> +    description: redefine rate of DSP system clock
>>>>
>>>> No vendor prefix, so is it a generic property? Also, missing unit
>>>> suffix, but more importantly I don't understand why this is a property
>>>> of hardware.
>>>
>>> +1.
>>>
>>> The appropriate way to set rate of the clock before the driver take over
>>> is 'assigned-rate', if you need to customize this for different
>>> platform.
>>>
>>
>> It would be great, but it doesn't work. Below, is what I want to see:
>>
>> 	assigned-clocks =
>> 		<&clkc_audio AUD2_CLKID_PDM_SYSCLK_SEL>,
>> 		<&clkc_audio AUD2_CLKID_PDM_SYSCLK_DIV>;
>> 	assigned-clock-parents =
>> 		<&clkc_pll CLKID_FCLK_DIV3>,
>> 		<0>;
>> 	assigned-clock-rates =
>> 		<0>,
>> 		<256000000>;
>>
>> But regardles of this declaration, PDM's driver unconditionally sets
>> sysclk'rate to 250MHz and throws away everything that was configured
>> before, reparents audio2_pdm_sysclk_mux to hifi_pll and changes
>> hifi_pll's rate.
>>
>> This value 250MHz is declared here:
>>
>> static const struct axg_pdm_cfg axg_pdm_config = {
>> 	.filters = &axg_default_filters,
>> 	.sys_rate = 250000000,
>> };
>>
>> The property 'sysrate' is intended to redefine hardcoded 'sys_rate'
>> value in 'axg_pdm_config'.
> 
> What is stopping you from removing that from the driver and adding
> assigned-rate to 250M is the existing platform ?
> 

Ok, in next version I will try to remove this unconditional setting of
rate that spoils my clock hierarchy.

>>
>>> Then you don't have to deal with it in the device driver.
>>>
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>
>>>
> 
> 

-- 
Best regards
Jan Dakinevich