[PATCH V3 3/6] clk: meson: S4: add support for Amlogic S4 SoC PLL clock driver
Yu Tu
yu.tu at amlogic.com
Tue Aug 30 00:37:26 PDT 2022
On 2022/8/30 14:44, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
>
>
> On Tue 30 Aug 2022 at 14:13, Yu Tu <yu.tu at amlogic.com> wrote:
>
>> On 2022/8/29 17:48, Jerome Brunet wrote:
>>> [ EXTERNAL EMAIL ]
>>> On Mon 15 Aug 2022 at 21:20, Yu Tu <yu.tu at amlogic.com> wrote:
>>>
>>>>>>> +
>>>>>>> +static struct clk_regmap s4_hdmi_pll_dco = {
>>>>>>> + .data = &(struct meson_clk_pll_data){
>>>>>>> + .en = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL0,
>>>>>>> + .shift = 28,
>>>>>>> + .width = 1,
>>>>>>> + },
>>>>>>> + .m = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL0,
>>>>>>> + .shift = 0,
>>>>>>> + .width = 8,
>>>>>>> + },
>>>>>>> + .n = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL0,
>>>>>>> + .shift = 10,
>>>>>>> + .width = 5,
>>>>>>> + },
>>>>>>> + .frac = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL1,
>>>>>>> + .shift = 0,
>>>>>>> + .width = 17,
>>>>>>> + },
>>>>>>> + .l = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL0,
>>>>>>> + .shift = 31,
>>>>>>> + .width = 1,
>>>>>>> + },
>>>>>>> + .rst = {
>>>>>>> + .reg_off = ANACTRL_HDMIPLL_CTRL0,
>>>>>>> + .shift = 29,
>>>>>>> + .width = 1,
>>>>>>> + },
>>>>>>> + },
>>>>>>> + .hw.init = &(struct clk_init_data){
>>>>>>> + .name = "hdmi_pll_dco",
>>>>>>> + .ops = &meson_clk_pll_ro_ops,
>>>>>>> + .parent_data = (const struct clk_parent_data []) {
>>>>>>> + { .fw_name = "xtal", }
>>>>>>> + },
>>>>>>> + .num_parents = 1,
>>>>>>> + /*
>>>>>>> + * Display directly handle hdmi pll registers ATM, we need
>>>>>>> + * NOCACHE to keep our view of the clock as accurate as
>>>>>>> + * possible
>>>>>>> + */
>>>>>>
>>>>>> Is it really ?
>>>>>>
>>>>>> Given that HDMI support for the s4 is there yet, the
>>>>>> addresses have changes and the region is no longer a syscon, it is time
>>>>>> for the HDMI driver to get fixed.
>>>> The HDMI PLL is configured in the Uboot phase and does not change the
>>>> frequency in the kernel phase. So we use the NOCACHE flag and
>>>> "ro_ops".
>>> That's no reason to put NOCACHE or ro-ops
>>> If you want the frequencies to be statically assinged, the correct way
>>> would be through assigned-rate in DT I guess.
>>
>> Okay. You're right. However, when registering with OPS, HDMI PLL will be
>> reset. It takes time for PLL to stabilize the output frequency, which will
>> lead to the startup screen flashing.
>>
>> I would like to know how to solve this problem if not using ro_ops.
>>
>>>
>
> You can add new ops or tweak the current init function.
HDMI PLL is not different from other PLLS, so I think adding OPS is weird.
>
> Safest would be to do the following :
> * Check if the PLLs is already on.
> * Check if the 'pll->init_regs' matches what is already set
> - if so, you can skip the reset
> - if not, you need to reset as usual
static int meson_clk_pll_init(struct clk_hw *hw)
{
struct clk_regmap *clk = to_clk_regmap(hw);
struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
if (pll->init_count) {
meson_parm_write(clk->map, &pll->rst, 1);
regmap_multi_reg_write(clk->map, pll->init_regs,
| pll->init_count);
meson_parm_write(clk->map, &pll->rst, 0);
}
return 0;
}
Because the init function looks like this. Therefore, HDMI PLL
init_count is not given. Can I change it like this?
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