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

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Message-ID: <CAA8EJprPeGMvN49HDEjc+cLSA+cwd=yDKOt2neFnuAmoO44gsw@mail.gmail.com>
Date: Wed, 3 Apr 2024 13:52:31 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Ajit Pandey <quic_ajipan@...cinc.com>
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 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?

> >>
> >>>> +
> >>>> +       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



-- 
With best wishes
Dmitry