linux-kernel - Re: [PATCH 7/7] clk: qcom: Add GPUCC driver support for SM4450

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Date: Wed, 3 Apr 2024 17:29:39 +0530
From: Ajit Pandey <quic_ajipan@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd
	<sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Vinod Koul <vkoul@...nel.org>,
        Vladimir Zapolskiy
	<vladimir.zapolskiy@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Taniya Das
	<quic_tdas@...cinc.com>,
        Jagadeesh Kona <quic_jkona@...cinc.com>,
        Imran Shaik
	<quic_imrashai@...cinc.com>,
        Satya Priya Kakitapalli
	<quic_skakitap@...cinc.com>
Subject: Re: [PATCH 7/7] clk: qcom: Add GPUCC driver support for SM4450



On 4/3/2024 4:22 PM, Dmitry Baryshkov wrote:
> On Wed, 3 Apr 2024 at 13:49, Ajit Pandey <quic_ajipan@...cinc.com> wrote:
>>
>>
>>
>> On 4/3/2024 12:53 AM, Dmitry Baryshkov wrote:
>>> On Tue, 2 Apr 2024 at 21:26, Ajit Pandey <quic_ajipan@...cinc.com> wrote:
>>>>
>>>>
>>>>
>>>> On 3/31/2024 7:09 AM, Dmitry Baryshkov wrote:
>>>>> On Sat, 30 Mar 2024 at 20:30, Ajit Pandey <quic_ajipan@...cinc.com> wrote:
>>>>>>
>>>>>> Add Graphics Clock Controller (GPUCC) support for SM4450 platform.
>>>>>>
>>>>>> Signed-off-by: Ajit Pandey <quic_ajipan@...cinc.com>
>>>>>> ---
>>>>>>     drivers/clk/qcom/Kconfig        |   9 +
>>>>>>     drivers/clk/qcom/Makefile       |   1 +
>>>>>>     drivers/clk/qcom/gpucc-sm4450.c | 806 ++++++++++++++++++++++++++++++++
>>>>>>     3 files changed, 816 insertions(+)
>>>>>>     create mode 100644 drivers/clk/qcom/gpucc-sm4450.c
>>>>>>
>>>>>
>>>>> [skipped]
>>>>>
>>>>>> +static int gpu_cc_sm4450_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> +       struct regmap *regmap;
>>>>>> +
>>>>>> +       regmap = qcom_cc_map(pdev, &gpu_cc_sm4450_desc);
>>>>>> +       if (IS_ERR(regmap))
>>>>>> +               return PTR_ERR(regmap);
>>>>>> +
>>>>>> +       clk_lucid_evo_pll_configure(&gpu_cc_pll0, regmap, &gpu_cc_pll0_config);
>>>>>> +       clk_lucid_evo_pll_configure(&gpu_cc_pll1, regmap, &gpu_cc_pll1_config);
>>>>>> +
>>>>>> +       /* Keep some clocks always enabled */
>>>>>> +       qcom_branch_set_clk_en(regmap, 0x93a4); /* GPU_CC_CB_CLK */
>>>>>> +       qcom_branch_set_clk_en(regmap, 0x9004); /* GPU_CC_CXO_AON_CLK */
>>>>>> +       qcom_branch_set_clk_en(regmap, 0x900c); /* GPU_CC_DEMET_CLK */
>>>>>
>>>>> Why? At least other drivers model these three clocks properly.
>>>>>
>>>> These clocks are POR on in SM4450 and required to be kept always enabled
>>>> for GPU functionality hence keep them enabled from probe only.
>>>
>>> Please, check how this is handled on the other platforms, please.
>>> Hint: `git grep GPU_CC_DEMET_CLK`
>>>
>> yeah these clocks are modeled and handled via always enabled clk ops
>> (clk_branch2_aon_ops) in few other platforms like SM8450, SM8650 which
>> also do same functionality and keep them in always enabled POR state,
>> while we kept them enabled from GPUCC probe in SM8550.
>> Since we need such clock to be always enabled irrespective of consumer
>> votes I guess modeling with aon_ops isn't really required and we can
>> simply keep them enabled in probe similar to other always on clocks.
> 
> Why are they required to be kept on even if there is no consumer?
>
We've GPU as consumer for these clocks but it's recommended to keep them
always enabled for basic GPU functionality as per HW recommendation.
Hence instead of modeling with _aon_ops we can simply keep them enabled 
all time from probe to avoid any issues.
>>>>
>>>>>> +
>>>>>> +       return qcom_cc_really_probe(pdev, &gpu_cc_sm4450_desc, regmap);
>>>>>> +}
>>>>>> +
>>>>>> +static struct platform_driver gpu_cc_sm4450_driver = {
>>>>>> +       .probe = gpu_cc_sm4450_probe,
>>>>>> +       .driver = {
>>>>>> +               .name = "gpucc-sm4450",
>>>>>> +               .of_match_table = gpu_cc_sm4450_match_table,
>>>>>> +       },
>>>>>> +};
>>>>>> +
>>>>>> +module_platform_driver(gpu_cc_sm4450_driver);
>>>>>> +
>>>>>> +MODULE_DESCRIPTION("QTI GPUCC SM4450 Driver");
>>>>>> +MODULE_LICENSE("GPL");
>>>>>> --
>>>>>> 2.25.1
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>> --
>>>> Thanks, and Regards
>>>> Ajit
>>>
>>>
>>>
>>
>> --
>> Thanks, and Regards
>> Ajit
> 
> 
> 

-- 
Thanks, and Regards
Ajit