linux-kernel - Re: [PATCH 05/10] clk: qcom: add Global Clock controller (GCC) driver for IPQ5332 SoC

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Message-ID: <37fccf60-75e7-3170-4e63-cafa62777596@quicinc.com>
Date:   Thu, 26 Jan 2023 22:15:00 +0530
From:   Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>
To:     Stephen Boyd <sboyd@...nel.org>, <agross@...nel.org>,
        <andersson@...nel.org>, <arnd@...db.de>,
        <bhupesh.sharma@...aro.org>, <broonie@...nel.org>,
        <catalin.marinas@....com>, <devicetree@...r.kernel.org>,
        <dmitry.baryshkov@...aro.org>, <konrad.dybcio@...aro.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <linus.walleij@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mmc@...r.kernel.org>, <marcel.ziswiler@...adex.com>,
        <mturquette@...libre.com>, <nfraprado@...labora.com>,
        <quic_gurus@...cinc.com>, <robh+dt@...nel.org>,
        <robimarko@...il.com>, <shawnguo@...nel.org>,
        <ulf.hansson@...aro.org>, <will@...nel.org>
Subject: Re: [PATCH 05/10] clk: qcom: add Global Clock controller (GCC) driver
 for IPQ5332 SoC


On 1/26/2023 2:24 AM, Stephen Boyd wrote:
> Quoting Kathiravan Thirumoorthy (2023-01-25 02:45:15)
>> diff --git a/drivers/clk/qcom/gcc-ipq5332.c b/drivers/clk/qcom/gcc-ipq5332.c
>> new file mode 100644
>> index 000000000000..8351096a4d32
>> --- /dev/null
>> +++ b/drivers/clk/qcom/gcc-ipq5332.c
>> @@ -0,0 +1,3954 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/regmap.h>
> [...]
>> +
>> +static const struct freq_tbl ftbl_gcc_pcnoc_bfdcd_clk_src[] = {
>> +       F(24000000, P_XO, 1, 0, 0),
>> +       F(50000000, P_GPLL0_OUT_MAIN, 16, 0, 0),
>> +       F(100000000, P_GPLL0_OUT_MAIN, 8, 0, 0),
>> +       { }
>> +};
>> +
>> +static struct clk_rcg2 gcc_pcnoc_bfdcd_clk_src = {
>> +       .cmd_rcgr = 0x31004,
>> +       .mnd_width = 0,
>> +       .hid_width = 5,
>> +       .parent_map = gcc_parent_map_0,
>> +       .freq_tbl = ftbl_gcc_pcnoc_bfdcd_clk_src,
>> +       .clkr.hw.init = &(const struct clk_init_data){
>> +               .name = "gcc_pcnoc_bfdcd_clk_src",
>> +               .parent_data = gcc_parent_data_0,
>> +               .num_parents = ARRAY_SIZE(gcc_parent_data_0),
>> +               .ops = &clk_rcg2_ops,
>> +               .flags = CLK_IS_CRITICAL,
> Why not just turn these clks on in probe and never register them with
> the framework? That saves some memory for clks that there is no desire
> to control from linux. This is an RCG, so in theory the frequency can
> change, but does it really? Usually bus clks are controlled by the
> interconnect driver.

Thanks Stephen for reviewing the patch. I will look into this and make 
changes appropriately in V2.