On 03/07/2019 01:28, Martin Blumenstingl wrote: > Hi Stephen, Hi Neil, > > On Mon, Jul 1, 2019 at 11:13 AM Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: >> >> In order to implement clock switching for the CLKID_CPU_CLK and >> CLKID_CPUB_CLK, notifiers are added on specific points of the >> clock tree : >> >> cpu_clk / cpub_clk >> | \- cpu_clk_dyn >> | | \- cpu_clk_premux0 >> | | |- cpu_clk_postmux0 >> | | | |- cpu_clk_dyn0_div >> | | | \- xtal/fclk_div2/fclk_div3 >> | | \- xtal/fclk_div2/fclk_div3 >> | \- cpu_clk_premux1 >> | |- cpu_clk_postmux1 >> | | |- cpu_clk_dyn1_div >> | | \- xtal/fclk_div2/fclk_div3 >> | \- xtal/fclk_div2/fclk_div3 >> \ sys_pll / sys1_pll >> >> This for each cluster, a single one for G12A, two for G12B. >> >> Each cpu_clk_premux1 tree is marked as read-only and CLK_SET_RATE_NO_REPARENT, >> to be used as "parking" clock in a safe clock frequency. > it seems that this is one case where the "coordinated clocks" feature > would come handy: [0] We could still migrate over it later on. > Stephen, do you know if those patches stopped in March or if there's > still some ongoing effort to get them ready? > > [...] >> -/* >> - * Internal sys pll emulation configuration parameters >> - */ >> -static const struct reg_sequence g12a_sys_init_regs[] = { >> - { .reg = HHI_SYS_PLL_CNTL1, .def = 0x00000000 }, >> - { .reg = HHI_SYS_PLL_CNTL2, .def = 0x00000000 }, >> - { .reg = HHI_SYS_PLL_CNTL3, .def = 0x48681c00 }, >> - { .reg = HHI_SYS_PLL_CNTL4, .def = 0x88770290 }, >> - { .reg = HHI_SYS_PLL_CNTL5, .def = 0x39272000 }, >> - { .reg = HHI_SYS_PLL_CNTL6, .def = 0x56540000 }, >> +static const struct pll_mult_range g12a_sys_pll_mult_range = { >> + .min = 128, >> + .max = 250, >> }; >> >> static struct clk_regmap g12a_sys_pll_dco = { >> @@ -124,14 +118,15 @@ static struct clk_regmap g12a_sys_pll_dco = { >> .shift = 29, >> .width = 1, >> }, >> - .init_regs = g12a_sys_init_regs, >> - .init_count = ARRAY_SIZE(g12a_sys_init_regs), >> + .range = &g12a_sys_pll_mult_range, > Neil, I believe that this should be a separate patch with a > description which explains why we don't need the "init regs" anymore Sure > >> }, >> .hw.init = &(struct clk_init_data){ >> .name = "sys_pll_dco", >> - .ops = &meson_clk_pll_ro_ops, >> + .ops = &meson_clk_pll_ops, >> .parent_names = (const char *[]){ IN_PREFIX "xtal" }, >> .num_parents = 1, >> + /* This clock feeds the CPU, avoid disabling it */ >> + .flags = CLK_IS_CRITICAL, > maybe we should have a separate patch for making the CPU clock tree > mutable as well Indeed > > [...] >> +/* This divider uses bit 26 to take change in account */ >> +static int g12b_cpub_clk_mux0_div_set_rate(struct clk_hw *hw, >> + unsigned long rate, >> + unsigned long parent_rate) >> +{ >> + struct clk_regmap *clk = to_clk_regmap(hw); >> + struct clk_regmap_div_data *div = clk_get_regmap_div_data(clk); >> + unsigned int val; >> + int ret; >> + >> + ret = divider_get_val(rate, parent_rate, div->table, div->width, >> + div->flags); >> + if (ret < 0) >> + return ret; >> + >> + val = (unsigned int)ret << div->shift; >> + >> + regmap_update_bits(clk->map, HHI_SYS_CPUB_CLK_CNTL, >> + SYS_CPU_DYN_ENABLE, SYS_CPU_DYN_ENABLE); >> + >> + return regmap_update_bits(clk->map, div->offset, >> + clk_div_mask(div->width) << div->shift | >> + SYS_CPU_DYN_ENABLE, val); >> +}; > the public S922X datasheet doesn't mention bit 26 > do I understand the semantics correctly?: > - set SYS_CPU_DYN_ENABLE > - update the divider > - unset SYS_CPU_DYN_ENABLE Exact, it's how Amlogic uses it, seems the HW takes the divider value only on the "falling edge" of this bit ! > > too bad it's not a gate which we could model with > CLK_SET_RATE_GATE/CLK_SET_RATE_UNGATE Yep, but it only works when I write the new divider value *and* I remove the bit. It must be a glitch-free divider mechanism. Neil > > > Martin > > [0] https://patchwork.kernel.org/patch/10838949/ >