linux-kernel - Re: [PATCH v1 1/1] soc/tegra: Add devm_tegra_core_dev_init_opp

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Date:   Mon, 17 May 2021 09:07:05 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Paul Fertser <fercerpav@...il.com>,
        Matt Merhar <mattmerhar@...tonmail.com>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] soc/tegra: Add
 devm_tegra_core_dev_init_opp_table()

I am not sure why you divided this into three different patchsets,
while it should really have been one. Like this one just adds the API
but doesn't use it.

On 16-05-21, 23:51, Dmitry Osipenko wrote:
> Add common helper which initializes OPP table for Tegra SoC core devices.
> 
> Tested-by: Peter Geis <pgwipeout@...il.com> # Ouya T30
> Tested-by: Paul Fertser <fercerpav@...il.com> # PAZ00 T20
> Tested-by: Nicolas Chauvet <kwizart@...il.com> # PAZ00 T20 and TK1 T124
> Tested-by: Matt Merhar <mattmerhar@...tonmail.com> # Ouya T30
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/soc/tegra/common.c | 112 +++++++++++++++++++++++++++++++++++++
>  include/soc/tegra/common.h |  30 ++++++++++
>  2 files changed, 142 insertions(+)
> 
> diff --git a/drivers/soc/tegra/common.c b/drivers/soc/tegra/common.c
> index 3dc54f59cafe..c3fd2facfc2d 100644
> --- a/drivers/soc/tegra/common.c
> +++ b/drivers/soc/tegra/common.c
> @@ -3,9 +3,16 @@
>   * Copyright (C) 2014 NVIDIA CORPORATION.  All rights reserved.
>   */
>  
> +#define dev_fmt(fmt)	"tegra-soc: " fmt
> +
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/export.h>
>  #include <linux/of.h>
> +#include <linux/pm_opp.h>
>  
>  #include <soc/tegra/common.h>
> +#include <soc/tegra/fuse.h>
>  
>  static const struct of_device_id tegra_machine_match[] = {
>  	{ .compatible = "nvidia,tegra20", },
> @@ -31,3 +38,108 @@ bool soc_is_tegra(void)
>  
>  	return match != NULL;
>  }
> +
> +static int tegra_core_dev_init_opp_state(struct device *dev)
> +{
> +	struct dev_pm_opp *opp;
> +	unsigned long rate;
> +	struct clk *clk;
> +	int err;
> +
> +	clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(dev, "failed to get clk: %pe\n", clk);
> +		return PTR_ERR(clk);
> +	}
> +
> +	rate = clk_get_rate(clk);
> +	if (!rate) {
> +		dev_err(dev, "failed to get clk rate\n");
> +		return -EINVAL;
> +	}
> +
> +	opp = dev_pm_opp_find_freq_ceil(dev, &rate);
> +
> +	if (opp == ERR_PTR(-ERANGE))
> +		opp = dev_pm_opp_find_freq_floor(dev, &rate);
> +
> +	err = PTR_ERR_OR_ZERO(opp);
> +	if (err) {
> +		dev_err(dev, "failed to get OPP for %ld Hz: %d\n",
> +			rate, err);
> +		return err;
> +	}

Why do you need to do this floor/ceil thing? Why can't you simply do
set-rate ? 

> +
> +	dev_pm_opp_put(opp);
> +
> +	/* first dummy rate-setting initializes voltage vote */
> +	err = dev_pm_opp_set_rate(dev, rate);
> +	if (err) {
> +		dev_err(dev, "failed to initialize OPP clock: %d\n", err);
> +		return err;
> +	}
> +
> +	return 0;
> +}

-- 
viresh