linux-kernel - Re: [PATCH 2/3] clk: meson: g12a: Add support for G12B CPUB clocks

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Date:   Tue, 21 May 2019 19:49:25 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     jbrunet@...libre.com, linux-amlogic@...ts.infradead.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] clk: meson: g12a: Add support for G12B CPUB clocks

Hi Neil,

On Tue, May 21, 2019 at 5:02 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>
> Update the Meson G12A Clock driver to support the Amlogic G12B SoC.
>
> G12B clock driver is very close, the main differences are :
> - the clock tree is duplicated for the both clusters, and the
>   SYS_PLL are swapped between the clusters
> - G12A has additional clocks like for CSI an other components
should this also be G12B?

[...]
> +static struct clk_regmap g12b_cpub_clk_apb_div = {
if you also think that it's worth it then please add a comment stating
that this is called "PCLK_mux" in the datasheet
same goes for the ATB and AXI clocks below as the naming in the driver
and datasheet differs

> +       .data = &(struct clk_regmap_div_data){
> +               .offset = HHI_SYS_CPUB_CLK_CNTL1,
> +               .shift = 3,
> +               .width = 3,
> +               .flags = CLK_DIVIDER_POWER_OF_TWO,
> +       },
> +       .hw.init = &(struct clk_init_data){
> +               .name = "cpub_clk_apb_div",
> +               .ops = &clk_regmap_divider_ro_ops,
> +               .parent_names = (const char *[]){ "cpub_clk" },
> +               .num_parents = 1,
> +       },
> +};
I'm assuming you checked that this is really a power of two divider,
on the Meson8/8b/8m2 SoCs this is a mux between div[2..8]
(the same goes for the ATB, AXI and trace div clocks below)

> +
> +static struct clk_regmap g12b_cpub_clk_apb = {
> +       .data = &(struct clk_regmap_gate_data){
> +               .offset = HHI_SYS_CPUB_CLK_CNTL1,
> +               .bit_idx = 16,
the public S922X datasheet calls this "PCLK_dis", does this mean you
need a flag here?
  .flags = CLK_GATE_SET_TO_DISABLE,

[...]
> +static struct clk_regmap g12b_cpub_clk_atb = {
> +       .data = &(struct clk_regmap_gate_data){
> +               .offset = HHI_SYS_CPUB_CLK_CNTL1,
> +               .bit_idx = 17,
the public S922X datasheet calls this "ATCLK_clk_dis", does this mean
you need a flag here?
  .flags = CLK_GATE_SET_TO_DISABLE,

[...]
> +static struct clk_regmap g12b_cpub_clk_axi = {
> +       .data = &(struct clk_regmap_gate_data){
> +               .offset = HHI_SYS_CPUB_CLK_CNTL1,
> +               .bit_idx = 18,
the public S922X datasheet calls this "ACLKM_clk_dis", does this mean
you need a flag here?
  .flags = CLK_GATE_SET_TO_DISABLE,

[...]
> +static struct clk_regmap g12b_cpub_clk_trace = {
> +       .data = &(struct clk_regmap_gate_data){
> +               .offset = HHI_SYS_CPUB_CLK_CNTL1,
> +               .bit_idx = 23,
the public S922X datasheet calls this "Trace_clk_dis", does this mean
you need a flag here?
  .flags = CLK_GATE_SET_TO_DISABLE,


Regards
Martin