linux-kernel - Re: [PATCH v1 2/2] leds: lgm: Add LED controller driver for LGM Soc

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Date:   Thu, 12 Nov 2020 06:34:23 +0800
From:   "Reddy, MallikarjunaX" <mallikarjunax.reddy@...ux.intel.com>
To:     Pavel Machek <pavel@....cz>
Cc:     linux-leds@...r.kernel.org, dmurphy@...com,
        devicetree@...r.kernel.org, robh+dt@...nel.org,
        linux-kernel@...r.kernel.org, cheol.yong.kim@...el.com,
        qi-ming.wu@...el.com, malliamireddy009@...il.com,
        yixin.zhu@...el.com
Subject: Re: [PATCH v1 2/2] leds: lgm: Add LED controller driver for LGM Soc

Hi Pavel,

Thanks for your valuable comments. My comments inline.

On 11/5/2020 6:11 PM, Pavel Machek wrote:
> Hi!
>
>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index ed943140e1fd..6445b39fe4fc 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -886,6 +886,16 @@ config LEDS_SGM3140
>>   	  This option enables support for the SGM3140 500mA Buck/Boost Charge
>>   	  Pump LED Driver.
>>   
>> +config LEDS_LGM_SSO
>> +	tristate "LED support for Intel LGM SOC series"
>> +	depends on LEDS_CLASS
>> +	depends on MFD_SYSCON
>> +	depends on OF
>> +	help
>> +          Parallel to serial conversion, which is also called SSO controller,
>> +          can drive external shift register for LED outputs.
>> +	  This enables LED support for Serial Shift Output Controller(SSO).
> Something is wrong with indentation here.
Seems tabbing.. i will fix it.
>
>> diff --git a/drivers/leds/leds-lgm-sso.c b/drivers/leds/leds-lgm-sso.c
> Could we put it into drivers/leds/blink/ directory? You'll need to
> create it.
Sure, i will update in the next patch.
>
>> index 000000000000..f1bae1c6ed3c
>> --- /dev/null
>> +++ b/drivers/leds/leds-lgm-sso.c
>> @@ -0,0 +1,881 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Intel LGM Soc LED SSO driver
> Spell out LGM, SSO. Soc->SoC.
>
> Pointer to documentation would be welcome here.
  Public documentation is not available.
>
>> +enum {
>> +	US_SW = 0,
>> +	US_GPTC = 1,
>> +	US_FPID = 2
>> +};
> This is not really useful without additional comments.
ok, i will update the additional comments.
>
>> +static u32 sso_rectify_brightness(u32 brightness)
>> +{
>> +	if (brightness > LED_FULL)
>> +		return LED_FULL;
>> +	else
>> +		return brightness;
>> +}
> Why?
As per below review comments if we use "default-state" property, it will 
be redundant.
>
>> +static int sso_rectify_blink_rate(struct sso_led_priv *priv, u32 rate)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < MAX_FREQ_RANK; i++) {
>> +		if (rate <= priv->freq[i])
>> +			return i;
>> +	}
>> +
>> +	return i - 1;
>> +}
> Can return -1. Is that expected?
It return the frequency index, if 'rate' is not matching with 
'priv->freq' it will return maximum index.
In case of return -1 need to adjust the code in the function from where 
it is called.

func name 'sso_get_blink_rate_idx' is more appropriate i think.
>
>> +
>> +		desc->np = to_of_node(fwnode_child);
>> +		if (fwnode_property_read_string(fwnode_child, "label",
>> +						&desc->name)) {
>> +			dev_err(dev, "LED no label name!\n");
>> +			goto __dt_err;
>> +		}
> Can you use appropriate helper from the core? labels are getting
> deprecated...
Agree.
>
>
>> +		if (fwnode_property_present(fwnode_child,
>> +					    "retain-state-suspended"))
>> +			desc->retain_state_suspended = 1;
> Was this documented in the binding?
No, i will udpate.
>
>> +		if (fwnode_property_read_u32(fwnode_child, "intel,led-pin",
>> +					     &prop)) {
>> +			dev_err(dev, "Failed to find led pin id!\n");
>> +			goto __dt_err;
> Would not we normally use something like reg = <x> to indicate pin?
Yes, we can do that. i will update in the next patch.
>
>> +		if (fwnode_property_present(fwnode_child,
>> +					    "intel,sso-hw-trigger"))
>> +			desc->hw_trig = 1;
> Should not that be selectable on runtime?
Agree, i will fix this.
>
>> +		if (fwnode_property_read_u32(fwnode_child,
>> +					     "intel,sso-brightness", &prop))
>> +			desc->brightness = priv->brightness;
>> +		else
>> +			desc->brightness = sso_rectify_brightness(prop);
> Can you look at "default-state" property?
sure. i will  update with "default-state" property
>
>> +	ret = sso_gpio_gc_init(dev, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
> Just return ret.
ok.
>
>> +
>> +	ret = clk_prepare_enable(priv->gclk);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to prepate/enable sso gate clock!\n");
>> +		return ret;
>> +	}
>> +
>> +	priv->fpid_clk = devm_clk_get(dev, "fpid");
>> +	if (IS_ERR(priv->fpid_clk)) {
>> +		dev_err(dev, "Failed to get fpid clock!\n");
>> +		return PTR_ERR(priv->fpid_clk);
>> +	}
> clk disable here?
ok. i will use devm_add_action_or_reset to disable clocks.
>
>> +	ret = clk_prepare_enable(priv->fpid_clk);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to prepare/enable fpid clock!\n");
>> +		return ret;
>> +	}
>> +	priv->fpid_clkrate = clk_get_rate(priv->fpid_clk);
>> +
>> +	priv->mmap = syscon_node_to_regmap(dev->of_node);
>> +	if (IS_ERR(priv->mmap)) {
>> +		dev_err(dev, "Failed to map iomem!\n");
>> +		return PTR_ERR(priv->mmap);
>> +	}
> clk disable here? ... and probably elsewhere?
ok. i will use devm_add_action_or_reset to disable clocks.
>
> Best regards,
> 							Pavel