linux-kernel - Re: [PATCH] gpio: brcmstb: support gpio-line-names property

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Message-ID: <810d8c3d-482f-078c-70b5-c4123c2679b8@gmail.com>
Date:   Mon, 9 Mar 2020 10:42:08 -0700
From:   Doug Berger <opendmb@...il.com>
To:     Gregory Fong <gregory.0xf0@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        linux-gpio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: brcmstb: support gpio-line-names property

On 3/9/20 12:45 AM, Gregory Fong wrote:
> Hi Doug,
> 
> On Fri, Mar 6, 2020 at 4:14 PM Doug Berger <opendmb@...il.com> wrote:
>>
>> The default handling of the gpio-line-names property by the
>> gpiolib-of implementation does not work with the multiple
>> gpiochip banks per device structure used by the gpio-brcmstb
>> driver.
>>
>> This commit adds driver level support for the device tree
>> property so that GPIO lines can be assigned friendly names.
>>
>> Signed-off-by: Doug Berger <opendmb@...il.com>
> 
> I've added a few comments below.  With the suggested updates:
> Acked-by: Gregory Fong <gregory.0xf0@...il.com>
> 
>> ---
>>  drivers/gpio/gpio-brcmstb.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/gpio/gpio-brcmstb.c b/drivers/gpio/gpio-brcmstb.c
>> index 05e3f99ae59c..e9ab246e2d42 100644
>> --- a/drivers/gpio/gpio-brcmstb.c
>> +++ b/drivers/gpio/gpio-brcmstb.c
>> @@ -603,6 +603,49 @@ static const struct dev_pm_ops brcmstb_gpio_pm_ops = {
>>         .resume_noirq = brcmstb_gpio_resume,
>>  };
>>
>> +static void brcmstb_gpio_set_names(struct device *dev,
>> +                                  struct brcmstb_gpio_bank *bank)
>> +{
>> +       struct device_node *np = dev->of_node;
>> +       const char **names;
>> +       int nstrings, base;
>> +       unsigned int i;
>> +
>> +       base = bank->id * MAX_GPIO_PER_BANK;
>> +
>> +       nstrings = of_property_count_strings(np, "gpio-line-names");
>> +       if (nstrings <= base)
>> +               /* Line names not present */
>> +               return;
>> +
>> +       names = devm_kcalloc(dev, MAX_GPIO_PER_BANK, sizeof(char *),
> 
> Please use sizeof(*names) instead of sizeof(char *).
Good idea. Will do.

> 
>> +                            GFP_KERNEL);
>> +       if (!names)
>> +               return;
>> +
>> +       /*
>> +        * Make sure to not index beyond the end of the number of descriptors
>> +        * of the GPIO device.
>> +        */
>> +       for (i = 0; i < bank->width; i++) {
>> +               const char *name;
>> +               int ret;
>> +
>> +               ret = of_property_read_string_index(np, "gpio-line-names",
>> +                                                   base + i, &name);
>> +               if (ret) {
>> +                       if (ret != -ENODATA)
>> +                               dev_err(dev, "unable to name line %d: %d\n",
>> +                                       i, ret);
> 
> Recommend adding the GPIO bank ID to this error message.
I'll use the absolute line number rather than the bank relative line
number to reduce confusion, but since it's different from your
suggestion I'll leave off your Ack in case you really want the bank
number for some reason.

> 
> Best regards,
> Gregory
> 
Thanks Gregory!
V2 coming soon.