linux-kernel - Re: [PATCH v3 7/7] clk: qcom: apcs-msm8916: use clk_parent

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Date:   Thu, 2 Jan 2020 23:47:47 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Niklas Cassel <niklas.cassel@...aro.org>
Cc:     Andy Gross <agross@...nel.org>, linux-arm-msm@...r.kernel.org,
        amit.kucheria@...aro.org, sboyd@...nel.org,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 7/7] clk: qcom: apcs-msm8916: use clk_parent_data to
 specify the parent

On Mon 25 Nov 05:59 PST 2019, Niklas Cassel wrote:

> Allow accessing the parent clock names required for the driver
> operation by using the device tree node, while falling back to
> the previous method of using names in the global name space.
> 
> This permits extending the driver to other platforms without having to
> modify its source code.
> 
> Co-developed-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
> Signed-off-by: Niklas Cassel <niklas.cassel@...aro.org>
> ---
> Changes since v2:
> -Use clk_parent_data when specifying clock parents.
> 
>  drivers/clk/qcom/apcs-msm8916.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/qcom/apcs-msm8916.c b/drivers/clk/qcom/apcs-msm8916.c
> index 46061b3d230e..bb91644edc00 100644
> --- a/drivers/clk/qcom/apcs-msm8916.c
> +++ b/drivers/clk/qcom/apcs-msm8916.c
> @@ -19,9 +19,9 @@
>  
>  static const u32 gpll0_a53cc_map[] = { 4, 5 };
>  
> -static const char * const gpll0_a53cc[] = {
> -	"gpll0_vote",
> -	"a53pll",
> +static const struct clk_parent_data pdata[] = {
> +	{ .fw_name = "aux", .name = "gpll0_vote", },
> +	{ .fw_name = "pll", .name = "a53pll", },
>  };
>  
>  /*
> @@ -51,6 +51,19 @@ static int qcom_apcs_msm8916_clk_probe(struct platform_device *pdev)
>  	struct clk_init_data init = { };
>  	int ret = -ENODEV;
>  
> +	/*
> +	 * This driver is defined by the devicetree binding
> +	 * Documentation/devicetree/bindings/mailbox/qcom,apcs-kpss-global.txt,
> +	 * however, this driver is registered as a platform device by
> +	 * qcom-apcs-ipc-mailbox.c. Because of this, when this driver
> +	 * uses dev_get_regmap() and devm_clk_get(), it has to send the parent
> +	 * device as argument.
> +	 * When registering with the clock framework, we cannot use this trick,
> +	 * since the clock framework always looks at dev->of_node when it tries
> +	 * to find parent clock names using clk_parent_data.
> +	 */
> +	dev->of_node = parent->of_node;
> +

With this hunk replaced by Stephen's patch for handling this in the
clock core I did some basic tests and things seems to work as expected.

Tested-by: Bjorn Andersson <bjorn.andersson@...aro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Regards,
Bjorn

>  	regmap = dev_get_regmap(parent, NULL);
>  	if (!regmap) {
>  		dev_err(dev, "failed to get regmap: %d\n", ret);
> @@ -62,8 +75,8 @@ static int qcom_apcs_msm8916_clk_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	init.name = "a53mux";
> -	init.parent_names = gpll0_a53cc;
> -	init.num_parents = ARRAY_SIZE(gpll0_a53cc);
> +	init.parent_data = pdata;
> +	init.num_parents = ARRAY_SIZE(pdata);
>  	init.ops = &clk_regmap_mux_div_ops;
>  	init.flags = CLK_SET_RATE_PARENT;
>  
> -- 
> 2.23.0
>