Re: [PATCH v6 3/6] clk: meson-axg: add clock controller drivers

Jerome Brunet
2017-12-11T09:46:06Z

On Mon, 2017-12-11 at 14:48 +0800, Yixun Lan wrote:
> From: Qiufang Dai <qiufang.dai@amlogic.com>
>
> Add clock controller drivers for Amlogic Meson-AXG SoC.
>
> Acked-by: Neil Armstrong <narmstrong@baylibre.com>
> Signed-off-by: Qiufang Dai <qiufang.dai@amlogic.com>
> Signed-off-by: Yixun Lan <yixun.lan@amlogic.com>
> ---
> arch/arm64/Kconfig.platforms | 1 +
> drivers/clk/meson/Kconfig | 8 +
> drivers/clk/meson/Makefile | 1 +
> drivers/clk/meson/axg.c | 944
> +++++++++++++++++++++++++++++++++++++++++++
> drivers/clk/meson/axg.h | 126 ++++++
> 5 files changed, 1080 insertions(+)
> create mode 100644 drivers/clk/meson/axg.c
> create mode 100644 drivers/clk/meson/axg.h

Overall, the changes looks good to me.
I still have a few comments which I'd like to see addressed quickly after this
series is merged

[...]

>
> +static struct meson_clk_pll axg_fixed_pll = {
> + .m = {
> + .reg_off = HHI_MPLL_CNTL,
> + .shift = 0,
> + .width = 9,
> + },
> + .n = {
> + .reg_off = HHI_MPLL_CNTL,
> + .shift = 9,
> + .width = 5,
> + },
> + .od = {
> + .reg_off = HHI_MPLL_CNTL,
> + .shift = 16,
> + .width = 2,
> + },
> + .lock = &clk_lock,
> + .hw.init = &(struct clk_init_data){
> + .name = "fixed_pll",
> + .ops = &meson_clk_pll_ro_ops,
> + .parent_names = (const char *[]){ "xtal" },
> + .num_parents = 1,
> + .flags = CLK_GET_RATE_NOCACHE,

Is the rate of this clock supposed to changed by something else than
the CCF after boot ?

If not, you should drop this flag.
Same comment goes for axg_sys_pll and axg_gp0_pll

> + },
> +};

[...]

> +/*
> + * FIXME The legacy composite clocks (e.g. clk81) are both PLL post-dividers
> + * and should be modeled with their respective PLLs via the forthcoming
> + * coordinated clock rates feature
> + */
> +static u32 mux_table_clk81[] = { 0, 2, 3, 4, 5, 6, 7 };
> +static const char * const clk81_parent_names[] = {
> + "xtal", "fclk_div7", "mpll1", "mpll2", "fclk_div4",
> + "fclk_div3", "fclk_div5"
> +};
> +
> +static struct clk_mux axg_mpeg_clk_sel = {
> + .reg = (void *)HHI_MPEG_CLK_CNTL,
> + .mask = 0x7,
> + .shift = 12,
> + .flags = CLK_MUX_READ_ONLY,
> + .table = mux_table_clk81,
> + .lock = &clk_lock,
> + .hw.init = &(struct clk_init_data){
> + .name = "mpeg_clk_sel",
> + .ops = &clk_mux_ro_ops,
> + /*
> + * bits 14:12 selects from 8 possible parents:
> + * xtal, 1'b0 (wtf), fclk_div7, mpll_clkout1, mpll_clkout2,
> + * fclk_div4, fclk_div3, fclk_div5
> + */

This comment is not necessary with table above.

> + .parent_names = clk81_parent_names,
> + .num_parents = ARRAY_SIZE(clk81_parent_names),
> + .flags = CLK_SET_RATE_NO_REPARENT,

With ro_ops, this flag is not necessary, consider removing it.

> + },
> +};
> +
>