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

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

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.

Best regards,
Krzysztof