Re: [PATCH 07/10] clk: qcom: Add graphics clock controller driver for SM8150

From: Stephen Boyd
Date: Wed May 27 2020 - 04:44:03 EST


Quoting Jonathan Marek (2020-05-24 14:06:08)
> diff --git a/drivers/clk/qcom/gpucc-sm8150.c b/drivers/clk/qcom/gpucc-sm8150.c
> new file mode 100644
> index 000000000000..6e1fff0cde75
> --- /dev/null
> +++ b/drivers/clk/qcom/gpucc-sm8150.c
> @@ -0,0 +1,429 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2017-2020, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <dt-bindings/clock/qcom,gpucc-sm8150.h>
[..]
> +
> +static struct clk_rcg2 gpu_cc_gmu_clk_src = {
> + .cmd_rcgr = 0x1120,
> + .mnd_width = 0,
> + .hid_width = 5,
> + .parent_map = gpu_cc_parent_map_0,
> + .freq_tbl = ftbl_gpu_cc_gmu_clk_src,
> + .clkr.hw.init = &(struct clk_init_data){
> + .name = "gpu_cc_gmu_clk_src",
> + .parent_names = gpu_cc_parent_names_0,
> + .num_parents = 6,
> + .flags = CLK_SET_RATE_PARENT,
> + .ops = &clk_rcg2_ops,
> + },
> +};
> +
> +static struct clk_branch gpu_cc_ahb_clk = {
> + .halt_reg = 0x1078,
> + .halt_check = BRANCH_HALT_DELAY,
> + .clkr = {
> + .enable_reg = 0x1078,
> + .enable_mask = BIT(0),
> + .hw.init = &(struct clk_init_data){
> + .name = "gpu_cc_ahb_clk",
> + .flags = CLK_IS_CRITICAL,

Why is this CLK_IS_CRITICAL? Why not just enable the clk manually with
a register write in probe and then remove this clk from the system? We
can save some memory that way.

> + .ops = &clk_branch2_ops,
> + },
> + },
> +};
> +
[...]
> +
> +static struct gdsc gpu_cx_gdsc = {
> + .gdscr = 0x106c,
> + .gds_hw_ctrl = 0x1540,
> + .pd = {
> + .name = "gpu_cx_gdsc",
> + },
> + .pwrsts = PWRSTS_OFF_ON,
> + .flags = VOTABLE,
> +};
> +
> +/* see comment in gpucc-sdm845 about this */
> +static int gx_gdsc_enable(struct generic_pm_domain *domain)
> +{
> + /* Do nothing but give genpd the impression that we were successful */
> + return 0;
> +}

Maybe we should export a helper from gdsc.c for this with the comment
and it named something obvious? gx_gdsc_do_nothing_enable()?

> +
> +static struct gdsc gpu_gx_gdsc = {
> + .gdscr = 0x100c,
> + .clamp_io_ctrl = 0x1508,
> + .pd = {
> + .name = "gpu_gx_gdsc",
> + .power_on = gx_gdsc_enable,
> + },
> + .pwrsts = PWRSTS_OFF_ON,
> + .flags = CLAMP_IO | AON_RESET | POLL_CFG_GDSCR,
> +};
> +