Message-ID: <2024130d-612e-9a3e-8c52-8982866e62f5@quicinc.com>
Date:   Wed, 18 Oct 2023 02:18:38 +0530
From:   Devi Priya <quic_devipriy@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC:     <andersson@...nel.org>, <agross@...nel.org>,
        <konrad.dybcio@...aro.org>, <mturquette@...libre.com>,
        <sboyd@...nel.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <p.zabel@...gutronix.de>, <richardcochran@...il.com>,
        <arnd@...db.de>, <geert+renesas@...der.be>,
        <nfraprado@...labora.com>, <rafal@...ecki.pl>, <peng.fan@....com>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <netdev@...r.kernel.org>,
        <quic_saahtoma@...cinc.com>
Subject: Re: [PATCH V2 5/7] clk: qcom: Add NSS clock Controller driver for
 IPQ9574



On 10/7/2023 2:51 AM, Dmitry Baryshkov wrote:
> On Thu, 5 Oct 2023 at 12:56, Devi Priya <quic_devipriy@...cinc.com> wrote:
>>
>>
>>
>> On 10/5/2023 12:49 PM, Dmitry Baryshkov wrote:
>>> On Thu, 5 Oct 2023 at 09:26, Devi Priya <quic_devipriy@...cinc.com> wrote:
>>>>
>>>>
>>>>
>>>> On 9/22/2023 5:31 PM, Devi Priya wrote:
>>>>>
>>>>>
>>>>> On 9/20/2023 1:50 PM, Dmitry Baryshkov wrote:
>>>>>> On Wed, 20 Sept 2023 at 09:39, Devi Priya <quic_devipriy@...cinc.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 9/12/2023 7:38 PM, Devi Priya wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 8/25/2023 5:14 PM, Dmitry Baryshkov wrote:
>>>>>>>>> On Fri, 25 Aug 2023 at 12:15, Devi Priya <quic_devipriy@...cinc.com>
>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>> Add Networking Sub System Clock Controller(NSSCC) driver for ipq9574
>>>>>>>>>> based
>>>>>>>>>> devices.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Devi Priya <quic_devipriy@...cinc.com>
>>>>>>>>>> ---
>>>>>>>>>>      Changes in V2:
>>>>>>>>>>             - Added depends on ARM64 || COMPILE_TEST in Kconfig
>>>>>>>>>>             - Added module_platform_driver
>>>>>>>>>>             - Dropped patch [2/6] - clk: qcom: gcc-ipq9574: Mark nssnoc
>>>>>>>>>> clocks as critical
>>>>>>>>>>                & added pm_clk for nssnoc clocks
>>>>>>>>>>             - Updated the uniphy clock names
>>>>>>>>>>
>>>>>>>>>>      drivers/clk/qcom/Kconfig         |    7 +
>>>>>>>>>>      drivers/clk/qcom/Makefile        |    1 +
>>>>>>>>>>      drivers/clk/qcom/nsscc-ipq9574.c | 3109
>>>>>>>>>> ++++++++++++++++++++++++++++++
>>>>>>>>>>      3 files changed, 3117 insertions(+)
>>>>>>>>>>      create mode 100644 drivers/clk/qcom/nsscc-ipq9574.c
>>>>>>>>>>
>>>>>>>>>> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
>>>>>>>>>> index bd9bfb11b328..3ecc11e2c8e3 100644
>>>>>>>>>> --- a/drivers/clk/qcom/Kconfig
>>>>>>>>>> +++ b/drivers/clk/qcom/Kconfig
>>>>>>>>>> @@ -203,6 +203,13 @@ config IPQ_GCC_9574
>>>>>>>>>>               i2c, USB, SD/eMMC, etc. Select this for the root clock
>>>>>>>>>>               of ipq9574.
>>>>>>>>>>
>>>>>>>>>> +config IPQ_NSSCC_9574
>>>>>>>>>> +       tristate "IPQ9574 NSS Clock Controller"
>>>>>>>>>> +       depends on ARM64 || COMPILE_TEST
>>>>>>>>>> +       depends on IPQ_GCC_9574
>>>>>>>>>> +       help
>>>>>>>>>> +         Support for NSS clock controller on ipq9574 devices.
>>>>>>>>>> +
>>>>>>>>>>      config MSM_GCC_8660
>>>>>>>>>>             tristate "MSM8660 Global Clock Controller"
>>>>>>>>>>             depends on ARM || COMPILE_TEST
>>>>>>>>>> diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
>>>>>>>>>> index 4790c8cca426..3f084928962e 100644
>>>>>>>>>> --- a/drivers/clk/qcom/Makefile
>>>>>>>>>> +++ b/drivers/clk/qcom/Makefile
>>>>>>>>>> @@ -30,6 +30,7 @@ obj-$(CONFIG_IPQ_GCC_6018) += gcc-ipq6018.o
>>>>>>>>>>      obj-$(CONFIG_IPQ_GCC_806X) += gcc-ipq806x.o
>>>>>>>>>>      obj-$(CONFIG_IPQ_GCC_8074) += gcc-ipq8074.o
>>>>>>>>>>      obj-$(CONFIG_IPQ_GCC_9574) += gcc-ipq9574.o
>>>>>>>>>> +obj-$(CONFIG_IPQ_NSSCC_9574)   += nsscc-ipq9574.o
>>>>>>>>>>      obj-$(CONFIG_IPQ_LCC_806X) += lcc-ipq806x.o
>>>>>>>>>>      obj-$(CONFIG_MDM_GCC_9607) += gcc-mdm9607.o
>>>>>>>>>>      obj-$(CONFIG_MDM_GCC_9615) += gcc-mdm9615.o
>>>>>>>>>> diff --git a/drivers/clk/qcom/nsscc-ipq9574.c
>>>>>>>>>> b/drivers/clk/qcom/nsscc-ipq9574.c
>>>>>>>>>> new file mode 100644
>>>>>>>>>> index 000000000000..65bdb449ae5f
>>>>>>>>>> --- /dev/null
>>>>>>>>>> +++ b/drivers/clk/qcom/nsscc-ipq9574.c
>>>>>>>>>> @@ -0,0 +1,3109 @@
>>>>>>>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>>>>>>>> +/*
>>>>>>>>>> + * Copyright (c) 2021, The Linux Foundation. All rights reserved.
>>>>>>>>>> + * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights
>>>>>>>>>> reserved.
>>>>>>>>>> + */
>>>>>>>>>> +
>>>>>>>>>> +#include <linux/clk-provider.h>
>>>>>>>>>> +#include <linux/err.h>
>>>>>>>>>> +#include <linux/kernel.h>
>>>>>>>>>> +#include <linux/module.h>
>>>>>>>>>> +#include <linux/of.h>
>>>>>>>>>> +#include <linux/of_device.h>
>>>>>>>>>> +#include <linux/regmap.h>
>>>>>>>>>> +#include <linux/pm_clock.h>
>>>>>>>>>> +#include <linux/pm_runtime.h>
>>>>>>>>>> +
>>>>>>>>>> +#include <dt-bindings/clock/qcom,ipq9574-nsscc.h>
>>>>>>>>>> +#include <dt-bindings/reset/qcom,ipq9574-nsscc.h>
>>>>>>>>>> +
>>>>>>>>>> +#include "clk-alpha-pll.h"
>>>>>>>>>> +#include "clk-branch.h"
>>>>>>>>>> +#include "clk-pll.h"
>>>>>>>>>> +#include "clk-rcg.h"
>>>>>>>>>> +#include "clk-regmap.h"
>>>>>>>>>> +#include "clk-regmap-divider.h"
>>>>>>>>>> +#include "clk-regmap-mux.h"
>>>>>>>>>> +#include "common.h"
>>>>>>>>>> +#include "reset.h"
>>>>>>>>>> +
>>>>>>>>>> +/* Need to match the order of clocks in DT binding */
>>>>>>>>>> +enum {
>>>>>>>>>> +       DT_NSSNOC_NSSCC_CLK,
>>>>>>>>>> +       DT_NSSNOC_SNOC_CLK,
>>>>>>>>>> +       DT_NSSNOC_SNOC_1_CLK,
>>>>>>>>>
>>>>>>>>> Not using the index makes it seem that these clocks are not used,
>>>>>>>>> until one scrolls down to pm_clks.
>>>>>>>> Okay, got it
>>>>>>>>>
>>>>>>>>> BTW: The NSSNOC_SNOC clocks make it look like there is an interconnect
>>>>>>>>> here (not a simple NIU).
>>>>>>>>
>>>>>>>> Hi Dmitry, We are exploring on the ICC driver. In the meantime to
>>>>>>>> unblock PCIe/NSS changes getting merged, shall we use
>>>>>>>> regmap_update_bits
>>>>>>>> and turn on the critical NSSNOC clocks, ANOC & SNOC pcie clocks in the
>>>>>>>> probe function of the gcc driver itself as like sm8550 driver to get
>>>>>>>> the
>>>>>>>> changes merged?
>>>>>>>>
>>>>>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/clk/qcom/gcc-sm8550.c#n3347
>>>>>>>
>>>>>>> Hi Dmitry,
>>>>>>> Just curious to know if we could send out the next series with the
>>>>>>> proposed approach if that holds good.
>>>>>>
>>>>>> The answer really depends on the structure of your hardware. The issue
>>>>>> is that once you commit the device bindings,you have to support them
>>>>>> forever. So, if you commit the NSS clock support without interconnects
>>>>>> in place, you have to keep this ANOC/SNOC/etc code forever, even after
>>>>>> you land the interconnect. So I'd suggest landing the icc driver first
>>>>>> (or at least implementing and sending to the mailing list), so that we
>>>>>> can see how all these pieces fit together.
>>>>>
>>>>> Hi Dmitry,
>>>>> Unlike MSM chipsets, IPQ chipsets does not have any use case wherein the
>>>>> NOC clocks have to be scaled. So if these clocks can be enabled in the
>>>>> probe, there is no need for an interconnect driver at all. The same
>>>>> applies to both ipq9574 and ipq5332 SoCs.
>>>>>
>>>>
>>>> Hi Dmitry,
>>>> Just curious to know if we can go ahead with the proposed solution of
>>>> enabling the NOC clocks in the probe as these clocks need not be scaled
>>>> in IPQ chipsets & hence there would be no need for an ICC driver in
>>>> ipq9574 & ipq5332 targets.
>>>
>>> In the probe of which driver?
>> GCC driver of ipq9574 & ipq5332 targets.
> 
> Would you need to handle these clocks additionally in the
> suspend/resume path? Will this increase the power consumption of the
> board?
> 
> Generally, I'd say this looks like a bad idea. Consider all the
> troubles we are undergoing now while sorting out the NIU clocks on RPM
> and RPMH platforms.
> So, unless you are 100% sure that this is a permanent solution (like
> AHB clocks being always on), I'd kindly suggest implementing the NoC
> attachment properly. In the end, other Qualcomm platforms use ICC
> drivers, so by following this pattern we will have more common code
> paths.
> 
Hi Dmitry,

Having these clocks always on seems to be a permanent solution and
we do not foresee any issues in our SoCs.

Thanks,
Devi Priya

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