linux-kernel - Re: [PATCH v10 0/4] clk: meson: add a sub EMMC clock controller support

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Message-ID: <27bf78f7-23b9-d759-28eb-0594006a30c6@amlogic.com>
Date:   Wed, 26 Jan 2022 17:42:17 +0800
From:   Liang Yang <liang.yang@...ogic.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, <linux-clk@...r.kernel.org>
CC:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Victor Wan <victor.wan@...ogic.com>,
        XianWei Zhao <xianwei.zhao@...ogic.com>,
        Kelvin Zhang <kelvin.zhang@...ogic.com>,
        BiChao Zheng <bichao.zheng@...ogic.com>,
        YongHui Yu <yonghui.yu@...ogic.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v10 0/4] clk: meson: add a sub EMMC clock controller
 support

Hi Jerome,

On 2022/1/26 17:14, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
> 
> 
> On Wed 26 Jan 2022 at 17:08, Liang Yang <liang.yang@...ogic.com> wrote:
> 
>> Hi Neil,
>>
>> On 2022/1/25 22:54, Neil Armstrong wrote:
>>> [ EXTERNAL EMAIL ]
>>> Hi Liang,
>>> On 21/01/2022 08:45, Liang Yang wrote:
>>>> This driver will add a MMC clock controller driver support.
>>>> The original idea about adding a clock controller is during the
>>>> discussion in the NAND driver mainline effort[1].
>>>>
>>>> This driver is tested in the S400 board (AXG platform) with NAND driver.
>>> Thanks a lot for providing a fixed and updated version of this serie.
>>> After some chat with Jerome and Kevin, it seems the way the eMMC clock
>>> reuse
>>> for NAND was designed nearly 4 years doesn't look accurate anymore.
>>> Having a separate clk driver designed to replace the eMMC node when NAND
>>> is
>>> used on the board seems over engineered.
>>> Actually having the clock code you add in this serie _but_ directly in
>>> the NAND looks far better, and more coherent since having Linux runtime
>>> detection of eMMC vs NAND will never happen and even this serie required
>>> some DT modification from the bootloader.
>>> I'll let Jerome or Kevin add more details if they want, but I think you
>>> should resurrect
>>> the work you pushed in [1] & [2] but:
>>> - passing the eMMC clk registers as a third "reg" cell
>> Does it just need to define a 'reg' resource in NFC node and not 'syscon'
>> here?
> 
> Yes
> 
>>> - passing the same "clocks" phandle as the eMMC node
>>> - adding the eMMC clock code in the NAND driver directly
>>> I'm open to discussions if you consider the current approach is still
>>> superior.
>>
>> I don't have persuasive ideas, but really it shares the common clock
>> implementation for both NFC and EMMC. and we don't need to paste the
>> same code in NFC and EMMC.
> 
> You don't need to copy everything. If I understood correctly, all the
> Rx/Tx should not be needed. Yes, there is some duplication as it stands but
> it allows to avoid coupling the MMC and NAND driver. We can still think
> about optimizing things later on. Let's get something simply working
> first.
ok. i will do it. thank you.
> 
>>
>>> Thanks,
>>> Neil
>>> [1]
>>> https://lore.kernel.org/r/20220106033130.37623-1-liang.yang@amlogic.com
>>> [2] https://lore.kernel.org/r/20220106032504.23310-1-liang.yang@amlogic.com
>>>
>>>>
>>>> Changes since v9 [10]
>>>>    - use clk_parent_data instead of parent_names
>>>>
>>>> Changes since v8 [9]
>>>>    - use MESON_SCLK_ONE_BASED instead of CLK_DIVIDER_ONE_BASED
>>>>    - use struct_size to caculate onecell_data
>>>>    - add clk-phase-delay.h
>>>>    - define CLK_DELAY_STEP_PS_GX and CLK_DELAY_STEP_PS_AXG
>>>>
>>>> Changes since v7 [8]
>>>>    - move meson_clk_get_phase_delay_data() from header to driver
>>>>    - CONFIG sclk-div with COMMON_CLK_AMLOGIC instead of COMMON_CLK_AMLOGIC_AUDIO
>>>>    - remove onecell date and ID for internal MUX clk
>>>>    - use helper for functions for ONE_BASED in sclk-div
>>>>    - add ONE_BASED support for duty cycle
>>>>
>>>> Changes since v6 [7]:
>>>>    - add one based support for sclk divier
>>>>    - alloc sclk in probe for multiple instance
>>>>    - fix coding styles
>>>>
>>>> Changes since v5 [6]:
>>>>    - remove divider ops with .init and use sclk_div instead
>>>>    - drop CLK_DIVIDER_ROUND_CLOSEST in mux and div
>>>>    - drop the useless type cast
>>>>
>>>> Changes since v4 [5]:
>>>>    - use struct parm in phase delay driver
>>>>    - remove 0 delay releted part in phase delay driver
>>>>    - don't rebuild the parent name once again
>>>>    - add divider ops with .init
>>>>
>>>> Changes since v3 [4]:
>>>>    - separate clk-phase-delay driver
>>>>    - replace clk_get_rate() with clk_hw_get_rate()
>>>>    - collect Rob's R-Y
>>>>    - drop 'meson-' prefix from compatible string
>>>>
>>>>    Changes since v2 [3]:
>>>>    - squash dt-binding clock-id patch
>>>>    - update license
>>>>    - fix alignment
>>>>    - construct a clk register helper() function
>>>>
>>>> Changes since v1 [2]:
>>>>    - implement phase clock
>>>>    - update compatible name
>>>>    - adjust file name
>>>>    - divider probe() into small functions, and re-use them
>>>>
>>>> [1] https://lkml.kernel.org/r/20180628090034.0637a062@xps13
>>>> [2] https://lkml.kernel.org/r/20180703145716.31860-1-yixun.lan@amlogic.com
>>>> [3] https://lkml.kernel.org/r/20180710163658.6175-1-yixun.lan@amlogic.com
>>>> [4] https://lkml.kernel.org/r/20180712211244.11428-1-yixun.lan@amlogic.com
>>>> [5] https://lkml.kernel.org/r/20180809070724.11935-4-yixun.lan@amlogic.com
>>>> [6] https://lkml.kernel.org/r/1539839245-13793-1-git-send-email-jianxin.pan@amlogic.com
>>>> [7] https://lkml.kernel.org/r/1541089855-19356-1-git-send-email-jianxin.pan@amlogic.com
>>>> [8] https://lkml.kernel.org/r/1544457877-51301-1-git-send-email-jianxin.pan@amlogic.com
>>>> [9] https://lkml.kernel.org/r/1545063850-21504-1-git-send-email-jianxin.pan@amlogic.com
>>>> [10] https://lore.kernel.org/all/20220113115745.45826-1-liang.yang@amlogic.com/
>>>> Liang Yang (4):
>>>>     clk: meson: add one based divider support for sclk
>>>>     clk: meson: add emmc sub clock phase delay driver
>>>>     clk: meson: add DT documentation for emmc clock controller
>>>>     clk: meson: add sub MMC clock controller driver
>>>>
>>>>    .../bindings/clock/amlogic,mmc-clkc.yaml      |  64 ++++
>>>>    drivers/clk/meson/Kconfig                     |  18 ++
>>>>    drivers/clk/meson/Makefile                    |   2 +
>>>>    drivers/clk/meson/clk-phase-delay.c           |  69 ++++
>>>>    drivers/clk/meson/clk-phase-delay.h           |  20 ++
>>>>    drivers/clk/meson/mmc-clkc.c                  | 302 ++++++++++++++++++
>>>>    drivers/clk/meson/sclk-div.c                  |  59 ++--
>>>>    drivers/clk/meson/sclk-div.h                  |   3 +
>>>>    include/dt-bindings/clock/amlogic,mmc-clkc.h  |  14 +
>>>>    9 files changed, 529 insertions(+), 22 deletions(-)
>>>>    create mode 100644 Documentation/devicetree/bindings/clock/amlogic,mmc-clkc.yaml
>>>>    create mode 100644 drivers/clk/meson/clk-phase-delay.c
>>>>    create mode 100644 drivers/clk/meson/clk-phase-delay.h
>>>>    create mode 100644 drivers/clk/meson/mmc-clkc.c
>>>>    create mode 100644 include/dt-bindings/clock/amlogic,mmc-clkc.h
>>>>
>>> .
> 
> .