Re: [PATCH V6 3/3] clk: meson: s4: add support for Amlogic S4 SoC peripheral clock controller

Jerome Brunet
2023-01-30T09:07:43Z

On Sat 28 Jan 2023 at 18:17, Yu Tu <yu.tu@amlogic.com> wrote:

> On 2023/1/20 17:47, Jerome Brunet wrote:
>> [ EXTERNAL EMAIL ]
>> On Fri 20 Jan 2023 at 11:33, Yu Tu <yu.tu@amlogic.com> wrote:
>>
>>> Hi
>>> On 2023/1/19 19:37, Jerome Brunet wrote:
>>>> [ EXTERNAL EMAIL ]
>>>> On Mon 16 Jan 2023 at 15:42, Yu Tu <yu.tu@amlogic.com> wrote:
>>>>
>>>>> Add the peripherals clock controller driver in the s4 SoC family.
>>>>>
>>>>> Signed-off-by: Yu Tu <yu.tu@amlogic.com>
>>>> [...]
>>>>
>>>>> +
>>>>> +/* Video Clocks */
>>>>> +static struct clk_regmap s4_vid_pll_div = {
>>>>> + .data = &(struct meson_vid_pll_div_data){
>>>>> + .val = {
>>>>> + .reg_off = CLKCTRL_VID_PLL_CLK_DIV,
>>>>> + .shift = 0,
>>>>> + .width = 15,
>>>>> + },
>>>>> + .sel = {
>>>>> + .reg_off = CLKCTRL_VID_PLL_CLK_DIV,
>>>>> + .shift = 16,
>>>>> + .width = 2,
>>>>> + },
>>>>> + },
>>>>> + .hw.init = &(struct clk_init_data) {
>>>>> + .name = "vid_pll_div",
>>>>> + /*
>>>>> + * The frequency division from the hdmi_pll clock to the vid_pll_div
>>>>> + * clock is the default value of this register. When designing the
>>>>> + * video module of the chip, a default value that can meet the
>>>>> + * requirements of the video module will be solidified according
>>>>> + * to the usage requirements of the chip, so as to facilitate chip
>>>>> + * simulation. So this is ro_ops.
>>>>> + * It is important to note that this clock is not used on this
>>>>> + * chip and is described only for the integrity of the clock tree.
>>>>> + */
>>>> If it is reset value and will be applicable to all the design, regarless
>>>> of the use-case, then yes RO ops is OK
>>>>
>>>> >From what I understand here, the value will depend on the use-case requirements.
>>>> This is a typical case where the DT prop "assigned-rate" should be used, not RO ops.
>>>
>>> Check the previous chip history, the actual scene is not used at all,
>>> basically is used in simulation. So the previous SOC was "ro_ops" without
>>> any problems. This S4 SOC is not actually useful either.
>>>
>>> So when you were upstream, you had no problem making "ro_ops". I wonder if
>>> I could delete this useless clock, so you don't have to worry about it.
>> I don't know what to make of this. What is the point of adding a useless
>> clock ?
>
> As explained earlier this "vid_pll_div" is actually used in chip
> emulation. So next I'd like to know what you suggest to do with the clock?
>

If it does not exist in the actual SoC, please remove it