linux-kernel - Re: [PATCH 3/9] clk: qcom: gcc-msm8998: Control MMSS and GPUSS GPLL0 outputs properly

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Date:   Thu, 22 Jun 2023 08:55:50 -0600
From:   Jeffrey Hugo <quic_jhugo@...cinc.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Taniya Das <tdas@...eaurora.org>
CC:     Marijn Suijten <marijn.suijten@...ainline.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/9] clk: qcom: gcc-msm8998: Control MMSS and GPUSS GPLL0
 outputs properly

On 6/22/2023 5:57 AM, Konrad Dybcio wrote:
> Up until now, we've been relying on some non-descript hardware magic
> to pinkypromise turn the clocks on for us. While new SoCs shine with
> that feature, MSM8998 can not always be fully trusted.
> 
> Register the MMSS and GPUSS GPLL0 legs with the CCF to allow for manual
> enable voting.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/clk/qcom/gcc-msm8998.c | 58 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 58 insertions(+)
> 
> diff --git a/drivers/clk/qcom/gcc-msm8998.c b/drivers/clk/qcom/gcc-msm8998.c
> index be024f8093c5..cccb19cae481 100644
> --- a/drivers/clk/qcom/gcc-msm8998.c
> +++ b/drivers/clk/qcom/gcc-msm8998.c
> @@ -25,6 +25,9 @@
>   #include "reset.h"
>   #include "gdsc.h"
>   
> +#define GCC_MMSS_MISC	0x0902C
> +#define GCC_GPU_MISC	0x71028
> +
>   static struct pll_vco fabia_vco[] = {
>   	{ 250000000, 2000000000, 0 },
>   	{ 125000000, 1000000000, 1 },
> @@ -1367,6 +1370,22 @@ static struct clk_branch gcc_boot_rom_ahb_clk = {
>   	},
>   };
>   
> +static struct clk_branch gcc_mmss_gpll0_div_clk = {
> +	.halt_check = BRANCH_HALT_DELAY,
> +	.clkr = {
> +		.enable_reg = 0x5200c,
> +		.enable_mask = BIT(0),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "gcc_mmss_gpll0_div_clk",
> +			.parent_hws = (const struct clk_hw *[]) {
> +				&gpll0_out_main.clkr.hw,
> +			},
> +			.num_parents = 1,
> +			.ops = &clk_branch2_ops,
> +		},
> +	},
> +};
> +
>   static struct clk_branch gcc_mmss_gpll0_clk = {
>   	.halt_check = BRANCH_HALT_DELAY,
>   	.clkr = {
> @@ -1395,6 +1414,38 @@ static struct clk_branch gcc_mss_gpll0_div_clk_src = {
>   	},
>   };
>   
> +static struct clk_branch gcc_gpu_gpll0_div_clk = {
> +	.halt_check = BRANCH_HALT_DELAY,
> +	.clkr = {
> +		.enable_reg = 0x5200c,
> +		.enable_mask = BIT(3),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "gcc_gpu_gpll0_div_clk",
> +			.parent_hws = (const struct clk_hw *[]) {
> +				&gpll0_out_main.clkr.hw,
> +			},
> +			.num_parents = 1,
> +			.ops = &clk_branch2_ops,
> +		},
> +	},
> +};
> +
> +static struct clk_branch gcc_gpu_gpll0_clk = {
> +	.halt_check = BRANCH_HALT_DELAY,
> +	.clkr = {
> +		.enable_reg = 0x5200c,
> +		.enable_mask = BIT(4),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "gcc_gpu_gpll0_clk",
> +			.parent_hws = (const struct clk_hw *[]) {
> +				&gpll0_out_main.clkr.hw,
> +			},
> +			.num_parents = 1,
> +			.ops = &clk_branch2_ops,
> +		},
> +	},
> +};
> +
>   static struct clk_branch gcc_blsp1_ahb_clk = {
>   	.halt_reg = 0x17004,
>   	.halt_check = BRANCH_HALT_VOTED,
> @@ -3080,6 +3131,9 @@ static struct clk_regmap *gcc_msm8998_clocks[] = {
>   	[AGGRE2_SNOC_NORTH_AXI] = &aggre2_snoc_north_axi_clk.clkr,
>   	[SSC_XO] = &ssc_xo_clk.clkr,
>   	[SSC_CNOC_AHBS_CLK] = &ssc_cnoc_ahbs_clk.clkr,
> +	[GCC_MMSS_GPLL0_DIV_CLK] = &gcc_mmss_gpll0_div_clk.clkr,
> +	[GCC_GPU_GPLL0_DIV_CLK] = &gcc_gpu_gpll0_div_clk.clkr,
> +	[GCC_GPU_GPLL0_CLK] = &gcc_gpu_gpll0_clk.clkr,
>   };
>   
>   static struct gdsc *gcc_msm8998_gdscs[] = {
> @@ -3235,6 +3289,10 @@ static int gcc_msm8998_probe(struct platform_device *pdev)
>   	if (ret)
>   		return ret;
>   
> +	/* Disable the GPLL0 active input to MMSS and GPU via MISC registers */
> +	regmap_write(regmap, GCC_MMSS_MISC, 0x10003);
> +	regmap_write(regmap, GCC_GPU_MISC, 0x10003);

I wonder, does this disrupt a handoff of an active display from the 
bootloader to Linux?