linux-kernel - Re: [PATCH 2/2] pwm: meson: support meson A1 SoC family

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Message-ID: <1jv848ezzo.fsf@starbuckisacylon.baylibre.com>
Date: Tue, 23 Apr 2024 19:35:15 +0200
From: Jerome Brunet <jbrunet@...libre.com>
To: George Stark <gnstark@...utedevices.com>
Cc: u.kleine-koenig@...gutronix.de, neil.armstrong@...aro.org,
 khilman@...libre.com, jbrunet@...libre.com,
 martin.blumenstingl@...glemail.com, thierry.reding@...il.com,
 hkallweit1@...il.com, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-amlogic@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, kernel@...utedevices.com, George Stark
 <gnstark@...rdevices.ru>, Dmitry Rokosov <ddrokosov@...utedevices.com>
Subject: Re: [PATCH 2/2] pwm: meson: support meson A1 SoC family


On Tue 23 Apr 2024 at 19:10, George Stark <gnstark@...utedevices.com> wrote:

> From: George Stark <gnstark@...rdevices.ru>
>
> Add a compatible string and configuration for the meson A1 SoC family
> PWM. Additionally, provide an external clock initialization helper
> specifically designed for these PWM IPs.
>
> Signed-off-by: George Stark <gnstark@...rdevices.ru>
> Signed-off-by: Dmitry Rokosov <ddrokosov@...utedevices.com>
> ---
>  drivers/pwm/pwm-meson.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index ea96c5973488..529a541ba7b6 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -462,6 +462,33 @@ static int meson_pwm_init_channels_meson8b_v2(struct pwm_chip *chip)
>  	return meson_pwm_init_clocks_meson8b(chip, mux_parent_data);
>  }
>  
> +static int meson_pwm_init_channels_ext_clock(struct pwm_chip *chip)

That kind on naming (ext) is almost sure to clash with whatever comes next.
Just use the name of the first SoC using the method, a1 for instance.

> +{
> +	struct device *dev = pwmchip_parent(chip);
> +	struct meson_pwm *meson = to_meson_pwm(chip);
> +	struct meson_pwm_channel *channels = meson->channels;
> +	struct clk_bulk_data *clks = NULL;
> +	unsigned int i;
> +	int res;
> +
> +	res = devm_clk_bulk_get_all(dev, &clks);
> +	if (res < 0) {
> +		dev_err(dev, "can't get device clocks\n");
> +		return res;
> +	}

I don't think allocating the 'clk_bulk_data *clks' is necessary or safe.
We know exactly how many clocks we expect, there is no need for a get all.

> +
> +	if (res != MESON_NUM_PWMS) {
> +		dev_err(dev, "clock count must be %d, got %d\n",
> +			MESON_NUM_PWMS, res);
> +		return -EINVAL;
> +	}

.. and this only catches the problem after the fact.

It is probably convinient but not necessary.

> +
> +	for (i = 0; i < MESON_NUM_PWMS; i++)
> +		channels[i].clk = clks[i].clk;

channels[i].clk could be assigned directly of_clk_get() using clock
indexes. No extra allocation needed.

> +
> +	return 0;
> +}
> +
>  static const struct meson_pwm_data pwm_meson8b_data = {
>  	.parent_names = { "xtal", NULL, "fclk_div4", "fclk_div3" },
>  	.channels_init = meson_pwm_init_channels_meson8b_legacy,
> @@ -500,11 +527,19 @@ static const struct meson_pwm_data pwm_meson8_v2_data = {
>  	.channels_init = meson_pwm_init_channels_meson8b_v2,
>  };
>  
> +static const struct meson_pwm_data pwm_meson_ext_clock_data = {
> +	.channels_init = meson_pwm_init_channels_ext_clock,
> +};
> +
>  static const struct of_device_id meson_pwm_matches[] = {
>  	{
>  		.compatible = "amlogic,meson8-pwm-v2",
>  		.data = &pwm_meson8_v2_data
>  	},
> +	{
> +		.compatible = "amlogic,meson-a1-pwm",
> +		.data = &pwm_meson_ext_clock_data
> +	},
>  	/* The following compatibles are obsolete */
>  	{
>  		.compatible = "amlogic,meson8b-pwm",


-- 
Jerome