linux-kernel - Re: [PATCH] clk: qcom: gcc-sdm660: Replace usage of parent

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Date:   Tue, 24 Aug 2021 22:46:17 +0200
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        angelogioacchino.delregno@...ainline.org
Subject: Re: [PATCH] clk: qcom: gcc-sdm660: Replace usage of parent_names

Hi Bjorn,

Thanks for this cleanup, that's needed and much appreciated!

On 8/24/21 5:06 PM, Bjorn Andersson wrote:
> Using parent_data and parent_hws, instead of parent_names, does protect
> against some cases of incompletely defined clock trees. While it turns
> out that the bug being chased this time was totally unrelated, this
> patch converts the SDM660 GCC driver to avoid such issues.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>


Tested-by: Marijn Suijten <marijn.suijten@...ainline.org>

On the Sony Xperia XA2 Ultra, bar the necessary change in the 14NM DSI 
PHY driver commented below.

> [..]
> -
> -static struct clk_fixed_factor xo = {
> -	.mult = 1,
> -	.div = 1,
> -	.hw.init = &(struct clk_init_data){
> -		.name = "xo",
> -		.parent_names = (const char *[]){ "xo_board" },
> -		.num_parents = 1,
> -		.ops = &clk_fixed_factor_ops,
> -	},
> -};


Removing the global "xo" clock makes it so that our 14nm DSI PHY does 
not have a parent clock anymore, as the clock is called "xo_board" 
nowadays ("xo" in the position of fw_name is, as you know, only local to 
this driver because it is named that way in the clock-names property). 
We (SoMainline) suffer the same DSI PHY hardcoding issue on many other 
boards and are at this point investigating whether to provide &xo_board 
in DT like any other sane driver.  Do you happen to know if work is 
already underway to tackle this?

>   static struct clk_alpha_pll gpll0_early = {
>   	.offset = 0x0,
>   	.regs = clk_alpha_pll_regs[CLK_ALPHA_PLL_TYPE_DEFAULT],
> @@ -158,7 +35,9 @@ static struct clk_alpha_pll gpll0_early = {
>   		.enable_mask = BIT(0),
>   		.hw.init = &(struct clk_init_data){
>   			.name = "gpll0_early",
> -			.parent_names = (const char *[]){ "xo" },
> +			.parent_data = &(const struct clk_parent_data){
> +				.fw_name = "xo",
> +			},


I wish we could use .parent_names for a list of .fw_name's too
> [..]
> @@ -265,7 +270,7 @@ static struct clk_rcg2 blsp1_qup1_i2c_apps_clk_src = {
>   	.freq_tbl = ftbl_blsp1_qup1_i2c_apps_clk_src,
>   	.clkr.hw.init = &(struct clk_init_data){
>   		.name = "blsp1_qup1_i2c_apps_clk_src",
> -		.parent_names = gcc_parent_names_xo_gpll0_gpll0_early_div,
> +		.parent_data = gcc_parent_data_xo_gpll0_gpll0_early_div,
>   		.num_parents = 3,


How about using ARRAY_SIZE(gcc_parent_data_xo_gpll0_gpll0_early_div) 
now?  Same for every other occurrence of this pattern.

- Marijn