linux-kernel - Re: [PATCH V2 1/2] pinctrl: qcom: spmi-gpio: correct parent irqspec translation

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Date:   Wed, 08 Sep 2021 12:58:07 +0530
From:   skakit@...eaurora.org
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        David Collins <collinsd@...eaurora.org>, kgunda@...eaurora.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH V2 1/2] pinctrl: qcom: spmi-gpio: correct parent irqspec
 translation

On 2021-09-03 23:39, Stephen Boyd wrote:
> Quoting satya priya (2021-09-02 02:15:05)
>> diff --git a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c 
>> b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> index 98bf0e2..dbae168 100644
>> --- a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> +++ b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> @@ -1,6 +1,6 @@
>>  // SPDX-License-Identifier: GPL-2.0-only
>>  /*
>> - * Copyright (c) 2012-2014, The Linux Foundation. All rights 
>> reserved.
>> + * Copyright (c) 2012-2014, 2016-2021 The Linux Foundation. All 
>> rights reserved.
>>   */
>> 
>>  #include <linux/gpio/driver.h>
>> @@ -14,6 +14,7 @@
>>  #include <linux/platform_device.h>
>>  #include <linux/regmap.h>
>>  #include <linux/slab.h>
>> +#include <linux/spmi.h>
>>  #include <linux/types.h>
>> 
>>  #include <dt-bindings/pinctrl/qcom,pmic-gpio.h>
>> @@ -171,6 +172,8 @@ struct pmic_gpio_state {
>>         struct pinctrl_dev *ctrl;
>>         struct gpio_chip chip;
>>         struct irq_chip irq;
>> +       u8 usid;
>> +       u8 pid_base;
>>  };
>> 
>>  static const struct pinconf_generic_params pmic_gpio_bindings[] = {
>> @@ -949,12 +952,36 @@ static int 
>> pmic_gpio_child_to_parent_hwirq(struct gpio_chip *chip,
>>                                            unsigned int *parent_hwirq,
>>                                            unsigned int *parent_type)
>>  {
>> -       *parent_hwirq = child_hwirq + 0xc0;
>> +       struct pmic_gpio_state *state = gpiochip_get_data(chip);
>> +
>> +       *parent_hwirq = child_hwirq + state->pid_base;
>>         *parent_type = child_type;
>> 
>>         return 0;
>>  }
>> 
>> +static void *pmic_gpio_populate_parent_fwspec(struct gpio_chip *chip,
>> +                                            unsigned int 
>> parent_hwirq,
>> +                                            unsigned int parent_type)
>> +{
>> +       struct pmic_gpio_state *state = gpiochip_get_data(chip);
>> +       struct irq_fwspec *fwspec;
>> +
>> +       fwspec = kzalloc(sizeof(*fwspec), GFP_KERNEL);
> 
> The implementation of gpiochip_populate_parent_fwspec_fourcell() uses
> kmalloc() here. Should we also do that? Presumably the fwspec will be
> set with the important parts so this will save a memset call.
> 

Using kmalloc also should be fine but I'd like to keep the kzalloc, the 
memset() operation takes some very small amount of time (once at boot 
per consumer irqspec).  kzalloc() is more deterministic and results in 
code that doesn't care if elements are added to the definition of struct 
irq_fwspec. It also ensures that all param[] elements are initialized to 
0.

>> +       if (!fwspec)
>> +               return NULL;
>> +
>> +       fwspec->fwnode = chip->irq.parent_domain->fwnode;
>> +
>> +       fwspec->param_count = 4;
>> +       fwspec->param[0] = state->usid;
>> +       fwspec->param[1] = parent_hwirq;
>> +       fwspec->param[2] = 0;
> 
> If the kzalloc stays, this can be dropped.
> 

I'll drop this and add a comment like this /* param[2] must be left as 0 
*/, so that future reviewers don't think that there is a typo in the 
indices going 0, 1, 3

>> +       fwspec->param[3] = parent_type;
>> +
>> +       return fwspec;
>> +}
>> +
>>  static int pmic_gpio_probe(struct platform_device *pdev)
>>  {
>>         struct irq_domain *parent_domain;