Re: [PATCH 2/4] clk: qcom: lpassaudiocc-sc7280: Add support for LPASS resets for QCM6490

[Taniya Das <quic_tdas@quicinc.com>]

On 6/16/2024 1:19 PM, Krzysztof Kozlowski wrote:
> On 10/06/2024 12:03, Taniya Das wrote:
>>
>>
>> On 5/31/2024 9:56 PM, Krzysztof Kozlowski wrote:
>>> On 31/05/2024 12:22, Taniya Das wrote:
>>>> On the QCM6490 boards the LPASS firmware controls the complete clock
>>>> controller functionalities. But the LPASS resets are required to be
>>>> controlled from the high level OS. The Audio SW driver should be able to
>>>> assert/deassert the audio resets as required. Thus in clock driver add
>>>> support for the same.
>>>>
>>>> Signed-off-by: Taniya Das <quic_tdas@quicinc.com>
>>>> ---
>>>>    drivers/clk/qcom/lpassaudiocc-sc7280.c | 28 ++++++++++++++++++++++++++
>>>>    1 file changed, 28 insertions(+)
>>>>
>>>> diff --git a/drivers/clk/qcom/lpassaudiocc-sc7280.c b/drivers/clk/qcom/lpassaudiocc-sc7280.c
>>>> index c43d0b1af7f7..7fdfd07c111c 100644
>>>> --- a/drivers/clk/qcom/lpassaudiocc-sc7280.c
>>>> +++ b/drivers/clk/qcom/lpassaudiocc-sc7280.c
>>>> @@ -1,6 +1,7 @@
>>>>    // SPDX-License-Identifier: GPL-2.0-only
>>>>    /*
>>>>     * Copyright (c) 2021, The Linux Foundation. All rights reserved.
>>>> + * Copyright (c) 2024, Qualcomm Innovation Center, Inc. All rights reserved.
>>>>     */
>>>>    
>>>>    #include <linux/clk-provider.h>
>>>> @@ -869,10 +870,36 @@ static struct platform_driver lpass_aon_cc_sc7280_driver = {
>>>>    	},
>>>>    };
>>>>    
>>>> +static const struct of_device_id lpass_audio_cc_qcm6490_match_table[] = {
>>>> +	{ .compatible = "qcom,qcm6490-lpassaudiocc" },
>>>> +	{ }
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, lpass_audio_cc_qcm6490_match_table);
>>>> +
>>>> +static int lpass_audio_cc_qcm6490_probe(struct platform_device *pdev)
>>>> +{
>>>> +	lpass_audio_cc_sc7280_regmap_config.name = "lpassaudio_cc_reset";
>>>> +	lpass_audio_cc_sc7280_regmap_config.max_register = 0xc8;
>>>> +
>>>> +	return qcom_cc_probe_by_index(pdev, 1, &lpass_audio_cc_reset_sc7280_desc);
>>>> +}
>>>> +
>>>> +static struct platform_driver lpass_audio_cc_qcm6490_driver = {
>>>> +	.probe = lpass_audio_cc_qcm6490_probe,
>>>> +	.driver = {
>>>> +		.name = "lpass_audio_cc-qcm6490",
>>>> +		.of_match_table = lpass_audio_cc_qcm6490_match_table,
>>>> +	},
>>>> +};
>>>> +
>>>>    static int __init lpass_audio_cc_sc7280_init(void)
>>>>    {
>>>>    	int ret;
>>>>    
>>>> +	ret = platform_driver_register(&lpass_audio_cc_qcm6490_driver);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>>    	ret = platform_driver_register(&lpass_aon_cc_sc7280_driver);
>>> Why this is a new platform driver?  There should be just one driver with
>>> different match data.
>>>
>>
>> The main problem for me is that the current board(QCM6490) needs to be
>> only support a subset of the entire(only resets) functionality the
>> SC7280. If I redesign the probe function to pick the match data then I
>> might accidentally break the existing functionalities on SC7280 boards.
> 
> That's not a reason to not implement changes. Test your changes first.
> 
>>
>> Hence I thought to have a separate driver registration which looked a
>> cleaner approach to go away from the "of_device_is_compatible".
> 
> No. You over complicate simple case introducing unusual pattern.
> 

Krzysztof, now I am introducing a match data approach to differentiate 
between SC7280 and QCM6490 for adding the reset functionality only to 
the later board.

v2 series: 
https://lore.kernel.org/lkml/20240816-qcm6490-lpass-reset-v1-0-a11f33cad3c5@quicinc.com/T/#t 


> Best regards,
> Krzysztof
> 

-- 
Thanks & Regards,
Taniya Das.